A liquid-phase isoelectric focusing electrophoresis system(Rotofor) was used as the prefractionation tool for the sample preparation in the MALDI-MS analysis of a protein mixture. Each fraction collected was then dire...A liquid-phase isoelectric focusing electrophoresis system(Rotofor) was used as the prefractionation tool for the sample preparation in the MALDI-MS analysis of a protein mixture. Each fraction collected was then directly subjected to MALDI-TOF-MS analysis. By this approach, we are able to resolve two types of hemoglobins, A and C, which cannot be successfully separated by means of the traditional SDS-PAGE method.展开更多
Blastomycosis and histoplasmosis manifest as lung and systemic fungal infections in mammals caused by Histoplasma capsulatum, and Blastomyces dermatitidis. These infections exhibit cross reactivity of antibodies which...Blastomycosis and histoplasmosis manifest as lung and systemic fungal infections in mammals caused by Histoplasma capsulatum, and Blastomyces dermatitidis. These infections exhibit cross reactivity of antibodies which makes a correct diagnosis potentially elusive. The purpose of this study was to gain an understanding of which isoelectric focusing fractions (RotoforTM) of B. dermatitidis were reactive or cross reactive with serum specimens from dogs infected with B. dermatitidis, H. capsulatum, and Cryptococcus neoformans. Three serum specimens from dogs that were infected with B. dermatitidis, two dogs infected with H. capsulatum, and one dog infected with C. neoformans were assayed against the 20 B. dermatitidis RotoforTM fractions. Reactivity was determined using the indirect enzyme linked immunoassay (ELISA). Reactivity with B. dermatitidis was found predominantly in the protein fractions 1 - 6, and cross reactivity with H. capsulatum, and C. neoformans sera was found within the B. dermatitidis protein fractions 15 - 19.展开更多
The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than th...The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc, which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations.展开更多
Yoon's equation which predicted point of zero charge of complex oxide should predict the zero point of net charge (ZPNC) of mixture of variable and permanent charge rather than the point of zero charge (PZC) of th...Yoon's equation which predicted point of zero charge of complex oxide should predict the zero point of net charge (ZPNC) of mixture of variable and permanent charge rather than the point of zero charge (PZC) of the variable charge component. The calculated values with modified Yoon's equation agreed with the experimental values.展开更多
Interestingly, antifungal protein AFP was purified from Aspergillus giganteus supernatants with modified isoelectric focusing procedure after adaptation of the secretion conditions. Subsequently, the antifungal activi...Interestingly, antifungal protein AFP was purified from Aspergillus giganteus supernatants with modified isoelectric focusing procedure after adaptation of the secretion conditions. Subsequently, the antifungal activity as well as the mode of action against Alternaria alternata was tested in vitro. Moreover, different concentrations of AFP were applied to banana fruits for 15 days at 20°C in vivo. Obtained results illustrated that A. giganteus was able to secrete about 39.78 ± 2.39 mg AFP·l-1 Olson medium. The employed ammonium sulfate (AS 75%) precipitation procedure followed by dialysis steps yielded about 16 - 22 mg AFP·l-1 culture supernatant with general mean of 18.67 ± 1.98 mg·l-1. The lost amount of AFP during purification using AS and 3KDa cut-off dialysis membrane is about 50% thus, purification procedure must be further improved. Indeed, concluded results from MIC and hyphal extension inhibition test noticed that AFP was efficiently affected by either growth or hyphae form of A. alternata in vitro. The MIC of AFP against A. alternata was 2μg·ml-1. However,short, thick and highly septated hyphae with damaged constricted apical regions extruding from condensed mycelium aggregates in treated hyphae compared to the untreated culture was remarkably shown. The mode of action of in vitro experiment manifested that AFP was effective to act the fungal cell and permeabilize the cell membrane of A. alternata. Furthermore, the in vivo experiment showed that AFP could reduce post-harvest decay on banana caused by A. alternata. AFP at concentration of 15 and 25 μg·ml-1 exhibit Alternaria decayed reduction by 45.45% and 77.27%, respectively. While no Alternaria decayed area was observed when 50 μg·ml-1 was applied during the storage time. Quantification of DNA by species-specific PCR could exude a positive correlation between the DNA amount and decayed area. In conclusion, AFP can be efficiently used as a bio-preservative agent during storage and handling of banana fruits, and considered as an excellent biological alternative to combat secondary growth of filamentous fungi.展开更多
Aluminum hydroxide adjuvant exhibits a poorly crystalline boehmite(PCB)structure,which demonstrates instability during prolonged storage.In the present study,we systematically investigated the quality alterations of t...Aluminum hydroxide adjuvant exhibits a poorly crystalline boehmite(PCB)structure,which demonstrates instability during prolonged storage.In the present study,we systematically investigated the quality alterations of the adjuvant stored at roo m temperature by analyzing its crystal structure,particle size distribution,electron microscopic characteristics,pH,isoelectric point(pI),and adsorption capacity.These assessments aimed to ensure the effectiveness and safety of vaccine production.Three batches of adjuvants were stored at room temperature for 15 months,and their changes were monitored using X-ray diffraction patterns,transmission electron microscopy(TEM),pH measurements,pI determination,and adsorption capacity analysis.X-ray diffraction revealed that the crystalline phases of aluminum hydroxide initially exhibited a PCB structure,which became progressively more ordered during storage.Notably,after 12 months,a new diffraction peak emerged at 18.2°2θ,with its intensity increasing over time.This corresponded to the formation of highly crystalline gibbsite and bayerite,which compromised the stability of the adjuvant.Furthermore,the pH and pI values decreased during storage,reflecting a decline in the chemical stability of the adjuvant.Comprising nanoparticles with a mean diameter of 130 nm,the adjuvant maintained a high surface area and excellent adsorption capacity.The adsorption rate at 8 mg BSA/mg Al3+consistently exceeded 97%,with no statistically significant differences observed between the adsorption capacities at 1 and 15 months(P>0.05).This indicated that the nanoparticle aluminum hydroxide adjuvant sustained high adsorption efficiency throughout the storage period,underscoring its reliability as a vaccine adsorbent.However,in the later stages of storage,the emergence of highly crystalline gibbsite and bayerite,coupled with declines in pH and pI,negatively impacted the adjuvant’s stability.Based on these findings,we recommended that aluminum hydroxide adjuvants should not be stored at room temperature for longer than 12 months to preserve their quality and efficacy.展开更多
The 33 ku protein, prepared from NaCI-treated PSII particles, has shown an single band by SDS-PAGE. After being dialyzed against the low-osmotic medium at 4癈, it has been found that the 33 ku protein degraded into se...The 33 ku protein, prepared from NaCI-treated PSII particles, has shown an single band by SDS-PAGE. After being dialyzed against the low-osmotic medium at 4癈, it has been found that the 33 ku protein degraded into several small fragments. This result suggests that the preparations of 33 ku protein probably contain some latent proteinases. it has also been found, by the 2-D electrophoresis and IEF, that the preparations of 33 ku protein not dialyzed against the low-osmotic medium contain several polypeptides with nearly the same molecular weight but not the same isoelectric point as the 33 ku protein.展开更多
Amphoteric polymer can be used as retanning agent in leather manufacture. It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fix...Amphoteric polymer can be used as retanning agent in leather manufacture. It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather. However, the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point (pI) hinder their wide application. Herein, we synthesized five amphoteric acrylic polymers (AAPs) by free radical copolymerization with acrylic acid and five different cationic acrylic monomers. The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated. The aggregation of AAPs in aqueous solution showed pH and concentration dependence. Light scattering analysis showed that Poly (AA-co-MAPTAC) and Poly (AA-co-DMAPMA) were in the shape of coiled linear flexible chains with small particle size (Rg 7.6 nm and 14.8 nm, respectively) near the pI. However, Poly (AA-co-DAC), Poly (AA-co-DMC) and Poly (AA-co- DMAEMA) were in the shape of hollow spheres and exhibited serious aggregation. Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs. Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pI. The results are expected to provide theoretical reference for the synthesis and widespread application of AAPs.展开更多
Amphoteric polymer can be used as retanning agent in leather manufacture.It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixa...Amphoteric polymer can be used as retanning agent in leather manufacture.It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather.However,the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point(pl)hinder their wide application.Herein,we synthesized five amphoteric acrylic polymers(AAPs)by free radical copolymerization with acrylic acid and five different cationic acrylic monomers.The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated.The aggregation of AAPs in aqueous solution showed pH and concentration dependence.Light scattering analysis showed that Poly(AAA-co-MAPTAC)and Poly(AA-co-DMAPMA)were in the shape of coiled linear flexible chains with small particle size(R_(g)7.6 nm and 14.8 nm,respectively)near the pl.However,Poly(AA-co-DAC),Poly(AA-co-DMC)and Poly(AA-co-DMAEMA)were in the shape of hollow spheres and exhibited serious aggregation.Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs.Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pl.The results are expected to provide theoretical reference for the synthesis and wide-spread application of AAPs.展开更多
The corrosion and passive behavior of HP-13Cr stainless steel(HP-13Cr SS)in formate annulus protection fluid was investigated.HP-13Cr SS exhibited good passive behavior in clean formate annulus protection fluid,which ...The corrosion and passive behavior of HP-13Cr stainless steel(HP-13Cr SS)in formate annulus protection fluid was investigated.HP-13Cr SS exhibited good passive behavior in clean formate annulus protection fluid,which was attributed to a thinner and more dense passive film mainly composed of Cr_(2)O_(3).In the formation water solution,the passive film was composed of metastable Cr(OH)3,which was explained by the isoelectric point theory,resulting in the deterioration of the passive behavior of HP-13Cr SS.When the formation water penetrated the formate annulus protection fluid,a large number of loose FeCO_(3)particles formed in the corrosion scales,thus HP-13Cr SS suffered severe corrosion.Therefore,avoiding formation water penetrating the formate annulus protection fluid is conducive to improving the service life of HP-13Cr SS oil tubes in extremely aggressive environment.展开更多
Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated...Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated PMOXA and SH-terminated PDMAEMA onto polydopamine-anchored substrates.The mixed-brush coating was characterized by variable-angle spectroscopic ellipsometry,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,zeta potential measurements,water contact angle,and atomic force microscopy.The mixed brushes showed tunable surface charge,wettability,and surface roughness,depending on the degree of PDMAEMA swelling under varying pH and ionic strength(Ⅰ).Then the adsorption behaviors of pepsin,bovine serum albumin(BSA),γ-globulin,and lysozyme,four very different proteins with regard to isoelectric point,on the mixed brushes coating were studied by using fluorescence microscopy and surface plasmon resonance.When the chain length of PDMAEMA was about twice as long as PMOXA,the mixed brushes not only had high adsorption capacity for pepsin,BSA,and y-globulin but also had a desorption efficiency of 86.9%,87.1%,and 93.5%,respectively.It is explained that electrostatic attraction between the protonated PDMAEMA and positively charged acidic proteins(pepsin and BSA,whose isoelectric points were below the pK_(a) of PDMAEMA)would drive the intensive adsorption(at pH 3,I=10^(-3)mol·L^(-1)for pepsin,and pH 5,I=10^(-5)mol·L^(-1)for BSA),while desorption was dominated by the hydrophilic PMOXA when PDMAEMA was shrinking(at pH 7,I=10^(-1)mol·L^(-1)for pepsin,and pH 9,I=10^(-1)mol·L^(-1)for BSA).Furthermore,the isoelectric precipitation led to the adsorption of neutral protein(γ-globulin,whose isoelectric point was near the pK_a of PDMAEMA)at pH 7,I=10^(-5)mol·L^(-1),while electrostatic repulsion and antifouling PMOXA triggered the desorption of y-globulin at pH 3,I-10^(-1)mol·L^(-1).However,alkaline protein(lysozyme,whose isoelectric point was higher than the pK_(a) of PDMAEMA)exhibited slight adsorption on PMOXA/PDMAEMA mixed brushes under test conditions,regardless of whether PMOXA or PDMAEMA occupied the outermost layer.The antibacterial property of the mixed brushes against Escherichia coli was investigated.PMOXA/PDMAEMA mixed brushes showed significant bactericidal activity at pH 3,I=10^(-3)mol·L^(-1),while the rinse of pH 9,I=10^(-1)mol·L^(-1)solution could remove most of the residual bacteria.This work not only enables controlled adsorption of proteins with different isoelectric points but also ensures that the surface of the coating is minimized from bacterial contamination.展开更多
Leaf acid phosphatase (APase) activities of 274 soybean genotypes were surveyed under field conditions with two levels of P supplies, and a nutrient solution culture experiment with eight selected genotypes was subseq...Leaf acid phosphatase (APase) activities of 274 soybean genotypes were surveyed under field conditions with two levels of P supplies, and a nutrient solution culture experiment with eight selected genotypes was subsequently conducted under greenhouse conditions to further characterize APase activity and its isoform expression induced by P starvation. Results from the field experiment showed that there was a great genotypic variation for leaf APase activity among the tested soybean genotypes from different origins, and APase activity in many of the tested genotypes (about 60%) was generally increased in the treatment without P fertilizer addition. Results from the nutrient solution culture experiment showed that APase activity in all the eight tested genotypes was generally enhanced by P starvation. Six isoforms of APases were detected in isoelectric focusing gels with samples from both young and old leaves. The activity of all the six isoforms was increased by P starvation, but no new APase isoform was induced. Our results suggest that leaf APase activity could serve as an enzymatic indicator of P starvation for soybean; the increase in leaf APase activity under low P stress was mainly caused by the increase in the activity of existing isoforms but not by the induction of new isoforms.展开更多
The flotation behavior of Xixia andalusite was studied with different collectors.The tests were conducted with a pure andalusite sample in micro-flotation cell and then with an ore sample in a mechanical flotation cel...The flotation behavior of Xixia andalusite was studied with different collectors.The tests were conducted with a pure andalusite sample in micro-flotation cell and then with an ore sample in a mechanical flotation cell.The surface charge was measured on pure andalusite sample and the isoelectric point（IEP） was found to be pH 5.2.Andalusite is floated with an amine collector above IEP where mineral surface is negatively charged.In contrast,an alkyl sulfonate collector（sodium dodecyl benzene sulfonate） is effective in the pH range where andalusite surface is positively charged.Furthermore,andalusite is floated with oleate in neutral and mildly alkaline pH values.55.3% Al2O3 is produced with 75.6% andalusite recovery when using the alkyl benzene sulfonate collector.Starch is found to be an effective depressant for gangue minerals in alkyl benzene sulfonate flotation.Moreover,slimes are found to have an adverse effect on the flotation of andalusite.Therefore,pretreatment by desliming and pre-float（to remove carbonaceous species） prior to andalusite flotation is necessary.展开更多
等电聚焦(isoelectric focusing,简称IFF)也称等电点分离。自1960年代初,瑞典学者首次合成两性载体(商品名称有Ampholine和Pharmalyte等)并成功地用于蛋白质分离以来,这项技术得以迅速发展和应用。由于其分辨力高,可用于混合物的分离或...等电聚焦(isoelectric focusing,简称IFF)也称等电点分离。自1960年代初,瑞典学者首次合成两性载体(商品名称有Ampholine和Pharmalyte等)并成功地用于蛋白质分离以来,这项技术得以迅速发展和应用。由于其分辨力高,可用于混合物的分离或鉴定,国外已应用此项技术对近交系动物进行生化标志基因监测。我们采用本实验室建立的聚丙烯酰胺凝胶等电聚焦技术对近交系小鼠SMMC/B的Hb基因位点进行遗传关系分析,并与常规聚丙烯酰胺凝胶电泳(polyacrylamide gel electrophoresis,PAGE)作分辨力比较。展开更多
A novel method is developed for electro-focusing and moving neutralization reaction boundary (MNRB) created with HCl and NaOH. The optimized conditions are screened out. By using this method, the experiments are perfo...A novel method is developed for electro-focusing and moving neutralization reaction boundary (MNRB) created with HCl and NaOH. The optimized conditions are screened out. By using this method, the experiments are performed on MNRB formed with HCl and NaOH in agarose gel. The experiments are quantitatively in coincidence with the predictions with the theory of moving chemical reaction boundary (MCRB).展开更多
The stability of aqueous nano alumina powder suspensions with and without dispersant tri-ammonium citrate (TAC) was investigated by measuring zeta potential at different pH values. The isoelectric point (IEP) of alumi...The stability of aqueous nano alumina powder suspensions with and without dispersant tri-ammonium citrate (TAC) was investigated by measuring zeta potential at different pH values. The isoelectric point (IEP) of alumina powder shifts towards more acidic pH range by adding TAC dispersant. The results illustrate that adsorption of TAC on alumina powder surface existed in the aqueous suspension, which leads to a high stability of the suspension.展开更多
Maximum lignocellulose yield of biomass sorghum [Sorghum bicolor L. (Moench.)] is hampered by complex biological phenomena related to rotation, nitrogen (N) fertilization, soil tillage, and excessive biomass removal. ...Maximum lignocellulose yield of biomass sorghum [Sorghum bicolor L. (Moench.)] is hampered by complex biological phenomena related to rotation, nitrogen (N) fertilization, soil tillage, and excessive biomass removal. The biochemical basis of the effects of agronomic practices on sorghum production was studied by the enzymology of the active peroxidase (EC 1.11.1.7) isoenzymes that synthesize lignin. All studied practices altered the peroxidase pI values. Control sorghum without rotation and without N fertilization had the most inhibited peroxidase with very low maximum velocity (Vmax) value (3.10 mmol·min﹣1), and very low lignin (857 kg·ha﹣1) yield, which could decrease soil organic carbon possibly leading to adverse changes in soil chemistry. Corn-sorghum rotations with and without N fertilization increased the Vmax values of peroxidase and lignin and cellulose yields. Rotated sorghum subjected to 50% residue return (the percentage of crop residue was returned to the plot immediately after grinding at harvest) and 280 kg·ha﹣1 N fertilization possessed very active peroxidase (Vmax value 66.4 mmole·min﹣1) and the highest lignin (1387 kg·ha﹣1) yield. The 25% residue return rate without N fertilization induced high lignin (1125 kg·ha﹣1) and cellulose (11,961 kg·ha﹣1) but the 25% residue return rate with 280 kg·ha﹣1 N fertilization induced lower lignin (1046 kg·ha﹣1) yield. Continuously cropped sorghum treated with 336 kg·N·ha﹣1 produced active peroxidase that shared competitive inhibition relationship with the peroxidase of the 84 kg·N·ha﹣1 treatment. Ridge tillage combined with 280 kg·ha﹣1 N fertilization under continuous sorghum resulted in inhibited peroxidase possessing low Vmax value (13.0 μmole·min﹣1). Changing to conventional tillage combined with 280 kg·ha﹣1 N fertilization relieved the inhibition and increased the Vmax value to 23.7 mmol·min﹣1. These biological anomalies of sorghum cell wall related to agronomic practices originated from doubly inhibited sorghum peroxidases. This understanding may guide the choice of sustainable agronomic practices for maximizing lignocellulose yields for the bioenergy industry while protecting the environment.展开更多
The thiol components of the nonhistone proteins prepared from isolated nuclei from rat liver, regenerating liver and hepatoma 223 cells have been investigated after reaction with radio labelled N-ethylmaleimide and 5-...The thiol components of the nonhistone proteins prepared from isolated nuclei from rat liver, regenerating liver and hepatoma 223 cells have been investigated after reaction with radio labelled N-ethylmaleimide and 5-5’-dithiobis-(2-nitrobenzoic acid) (DTNB). The labelled adducts formed were examined by isoelectric focusing analysis in polyacrylamide gel and the distribution of the radiolabels within sliced portions of the gels determined. In the case of the 14C labelled NEM adduct the label was found to be spread amongst numerous protein components within the gel however, in the case of the 35S labelled DTNB adducts, only a small proportion of the label was found in the protein material which was retained in the acidic isoelectric point (pI) region of the gel. The bulk of the 35S labelled adduct (56% - 60%) was found to have migrated into the anode solution (10 mM phosphoric acid). This could be adsorbed onto a hydrophobic resin (XAD2) resin and eluted with methanol. Gel filtration chromatographic analysis of this adduct material on BioGel P2, (exclusion limit 1500 daltons) showed low molecular weight components to be present. Slightly different patterns were obtained for these nuclei, each containing several 35S components with molecular weights greater than the Ellman reagent itself. These 35S labelled thiol components did not contain any protein, peptide or amino acid components indicating strongly that a novel species of thiols could be present in these nuclei bound within the non-histone protein matrices.展开更多
The distribution of salivary acidic proline-rich proteins pheno-types was investigated by using the ultra-thin PAGIEF technique in 258 ChineseHan populations in Liaoning area. The gene frequencies were as follows: Pr^...The distribution of salivary acidic proline-rich proteins pheno-types was investigated by using the ultra-thin PAGIEF technique in 258 ChineseHan populations in Liaoning area. The gene frequencies were as follows: Pr^10.8101, Pr^20.1899; Db^+0.0416, Db^-0.9584; Pa^+0.1717, Pa^-0.8283; PIF^+0.6647, PIF^-0.3353. The observed numbers of the phenotypes are in good a-greement with the expected numbers under the Hardy-Weinberg equilibrium.The gene frequencies among the Chinese and other populations are compared.展开更多
文摘A liquid-phase isoelectric focusing electrophoresis system(Rotofor) was used as the prefractionation tool for the sample preparation in the MALDI-MS analysis of a protein mixture. Each fraction collected was then directly subjected to MALDI-TOF-MS analysis. By this approach, we are able to resolve two types of hemoglobins, A and C, which cannot be successfully separated by means of the traditional SDS-PAGE method.
文摘Blastomycosis and histoplasmosis manifest as lung and systemic fungal infections in mammals caused by Histoplasma capsulatum, and Blastomyces dermatitidis. These infections exhibit cross reactivity of antibodies which makes a correct diagnosis potentially elusive. The purpose of this study was to gain an understanding of which isoelectric focusing fractions (RotoforTM) of B. dermatitidis were reactive or cross reactive with serum specimens from dogs infected with B. dermatitidis, H. capsulatum, and Cryptococcus neoformans. Three serum specimens from dogs that were infected with B. dermatitidis, two dogs infected with H. capsulatum, and one dog infected with C. neoformans were assayed against the 20 B. dermatitidis RotoforTM fractions. Reactivity was determined using the indirect enzyme linked immunoassay (ELISA). Reactivity with B. dermatitidis was found predominantly in the protein fractions 1 - 6, and cross reactivity with H. capsulatum, and C. neoformans sera was found within the B. dermatitidis protein fractions 15 - 19.
文摘The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc, which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations.
文摘Yoon's equation which predicted point of zero charge of complex oxide should predict the zero point of net charge (ZPNC) of mixture of variable and permanent charge rather than the point of zero charge (PZC) of the variable charge component. The calculated values with modified Yoon's equation agreed with the experimental values.
文摘Interestingly, antifungal protein AFP was purified from Aspergillus giganteus supernatants with modified isoelectric focusing procedure after adaptation of the secretion conditions. Subsequently, the antifungal activity as well as the mode of action against Alternaria alternata was tested in vitro. Moreover, different concentrations of AFP were applied to banana fruits for 15 days at 20°C in vivo. Obtained results illustrated that A. giganteus was able to secrete about 39.78 ± 2.39 mg AFP·l-1 Olson medium. The employed ammonium sulfate (AS 75%) precipitation procedure followed by dialysis steps yielded about 16 - 22 mg AFP·l-1 culture supernatant with general mean of 18.67 ± 1.98 mg·l-1. The lost amount of AFP during purification using AS and 3KDa cut-off dialysis membrane is about 50% thus, purification procedure must be further improved. Indeed, concluded results from MIC and hyphal extension inhibition test noticed that AFP was efficiently affected by either growth or hyphae form of A. alternata in vitro. The MIC of AFP against A. alternata was 2μg·ml-1. However,short, thick and highly septated hyphae with damaged constricted apical regions extruding from condensed mycelium aggregates in treated hyphae compared to the untreated culture was remarkably shown. The mode of action of in vitro experiment manifested that AFP was effective to act the fungal cell and permeabilize the cell membrane of A. alternata. Furthermore, the in vivo experiment showed that AFP could reduce post-harvest decay on banana caused by A. alternata. AFP at concentration of 15 and 25 μg·ml-1 exhibit Alternaria decayed reduction by 45.45% and 77.27%, respectively. While no Alternaria decayed area was observed when 50 μg·ml-1 was applied during the storage time. Quantification of DNA by species-specific PCR could exude a positive correlation between the DNA amount and decayed area. In conclusion, AFP can be efficiently used as a bio-preservative agent during storage and handling of banana fruits, and considered as an excellent biological alternative to combat secondary growth of filamentous fungi.
文摘Aluminum hydroxide adjuvant exhibits a poorly crystalline boehmite(PCB)structure,which demonstrates instability during prolonged storage.In the present study,we systematically investigated the quality alterations of the adjuvant stored at roo m temperature by analyzing its crystal structure,particle size distribution,electron microscopic characteristics,pH,isoelectric point(pI),and adsorption capacity.These assessments aimed to ensure the effectiveness and safety of vaccine production.Three batches of adjuvants were stored at room temperature for 15 months,and their changes were monitored using X-ray diffraction patterns,transmission electron microscopy(TEM),pH measurements,pI determination,and adsorption capacity analysis.X-ray diffraction revealed that the crystalline phases of aluminum hydroxide initially exhibited a PCB structure,which became progressively more ordered during storage.Notably,after 12 months,a new diffraction peak emerged at 18.2°2θ,with its intensity increasing over time.This corresponded to the formation of highly crystalline gibbsite and bayerite,which compromised the stability of the adjuvant.Furthermore,the pH and pI values decreased during storage,reflecting a decline in the chemical stability of the adjuvant.Comprising nanoparticles with a mean diameter of 130 nm,the adjuvant maintained a high surface area and excellent adsorption capacity.The adsorption rate at 8 mg BSA/mg Al3+consistently exceeded 97%,with no statistically significant differences observed between the adsorption capacities at 1 and 15 months(P>0.05).This indicated that the nanoparticle aluminum hydroxide adjuvant sustained high adsorption efficiency throughout the storage period,underscoring its reliability as a vaccine adsorbent.However,in the later stages of storage,the emergence of highly crystalline gibbsite and bayerite,coupled with declines in pH and pI,negatively impacted the adjuvant’s stability.Based on these findings,we recommended that aluminum hydroxide adjuvants should not be stored at room temperature for longer than 12 months to preserve their quality and efficacy.
文摘The 33 ku protein, prepared from NaCI-treated PSII particles, has shown an single band by SDS-PAGE. After being dialyzed against the low-osmotic medium at 4癈, it has been found that the 33 ku protein degraded into several small fragments. This result suggests that the preparations of 33 ku protein probably contain some latent proteinases. it has also been found, by the 2-D electrophoresis and IEF, that the preparations of 33 ku protein not dialyzed against the low-osmotic medium contain several polypeptides with nearly the same molecular weight but not the same isoelectric point as the 33 ku protein.
基金the Tianfu Ten-thousand Talents Program of Sichuan Province and the National Key R&D Program(2017YFB0308500).
文摘Amphoteric polymer can be used as retanning agent in leather manufacture. It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather. However, the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point (pI) hinder their wide application. Herein, we synthesized five amphoteric acrylic polymers (AAPs) by free radical copolymerization with acrylic acid and five different cationic acrylic monomers. The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated. The aggregation of AAPs in aqueous solution showed pH and concentration dependence. Light scattering analysis showed that Poly (AA-co-MAPTAC) and Poly (AA-co-DMAPMA) were in the shape of coiled linear flexible chains with small particle size (Rg 7.6 nm and 14.8 nm, respectively) near the pI. However, Poly (AA-co-DAC), Poly (AA-co-DMC) and Poly (AA-co- DMAEMA) were in the shape of hollow spheres and exhibited serious aggregation. Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs. Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pI. The results are expected to provide theoretical reference for the synthesis and widespread application of AAPs.
基金supported by the Tianfu Ten-thousand Talents Program of Sichuan Province and the National Key R&D Program(2017YFB0308500).
文摘Amphoteric polymer can be used as retanning agent in leather manufacture.It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather.However,the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point(pl)hinder their wide application.Herein,we synthesized five amphoteric acrylic polymers(AAPs)by free radical copolymerization with acrylic acid and five different cationic acrylic monomers.The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated.The aggregation of AAPs in aqueous solution showed pH and concentration dependence.Light scattering analysis showed that Poly(AAA-co-MAPTAC)and Poly(AA-co-DMAPMA)were in the shape of coiled linear flexible chains with small particle size(R_(g)7.6 nm and 14.8 nm,respectively)near the pl.However,Poly(AA-co-DAC),Poly(AA-co-DMC)and Poly(AA-co-DMAEMA)were in the shape of hollow spheres and exhibited serious aggregation.Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs.Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pl.The results are expected to provide theoretical reference for the synthesis and wide-spread application of AAPs.
基金supported by the Youth Program of the National Natural Science Foundation of China(No.52001061)the Young Elite Scientist Sponsorship Program Cast(No.YESS20200139)the Fundamental Research Funds for the Central Universities(No.N2202016).
文摘The corrosion and passive behavior of HP-13Cr stainless steel(HP-13Cr SS)in formate annulus protection fluid was investigated.HP-13Cr SS exhibited good passive behavior in clean formate annulus protection fluid,which was attributed to a thinner and more dense passive film mainly composed of Cr_(2)O_(3).In the formation water solution,the passive film was composed of metastable Cr(OH)3,which was explained by the isoelectric point theory,resulting in the deterioration of the passive behavior of HP-13Cr SS.When the formation water penetrated the formate annulus protection fluid,a large number of loose FeCO_(3)particles formed in the corrosion scales,thus HP-13Cr SS suffered severe corrosion.Therefore,avoiding formation water penetrating the formate annulus protection fluid is conducive to improving the service life of HP-13Cr SS oil tubes in extremely aggressive environment.
基金the financial support of the National Natural Science Foundation of China(21674102)。
文摘Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated PMOXA and SH-terminated PDMAEMA onto polydopamine-anchored substrates.The mixed-brush coating was characterized by variable-angle spectroscopic ellipsometry,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,zeta potential measurements,water contact angle,and atomic force microscopy.The mixed brushes showed tunable surface charge,wettability,and surface roughness,depending on the degree of PDMAEMA swelling under varying pH and ionic strength(Ⅰ).Then the adsorption behaviors of pepsin,bovine serum albumin(BSA),γ-globulin,and lysozyme,four very different proteins with regard to isoelectric point,on the mixed brushes coating were studied by using fluorescence microscopy and surface plasmon resonance.When the chain length of PDMAEMA was about twice as long as PMOXA,the mixed brushes not only had high adsorption capacity for pepsin,BSA,and y-globulin but also had a desorption efficiency of 86.9%,87.1%,and 93.5%,respectively.It is explained that electrostatic attraction between the protonated PDMAEMA and positively charged acidic proteins(pepsin and BSA,whose isoelectric points were below the pK_(a) of PDMAEMA)would drive the intensive adsorption(at pH 3,I=10^(-3)mol·L^(-1)for pepsin,and pH 5,I=10^(-5)mol·L^(-1)for BSA),while desorption was dominated by the hydrophilic PMOXA when PDMAEMA was shrinking(at pH 7,I=10^(-1)mol·L^(-1)for pepsin,and pH 9,I=10^(-1)mol·L^(-1)for BSA).Furthermore,the isoelectric precipitation led to the adsorption of neutral protein(γ-globulin,whose isoelectric point was near the pK_a of PDMAEMA)at pH 7,I=10^(-5)mol·L^(-1),while electrostatic repulsion and antifouling PMOXA triggered the desorption of y-globulin at pH 3,I-10^(-1)mol·L^(-1).However,alkaline protein(lysozyme,whose isoelectric point was higher than the pK_(a) of PDMAEMA)exhibited slight adsorption on PMOXA/PDMAEMA mixed brushes under test conditions,regardless of whether PMOXA or PDMAEMA occupied the outermost layer.The antibacterial property of the mixed brushes against Escherichia coli was investigated.PMOXA/PDMAEMA mixed brushes showed significant bactericidal activity at pH 3,I=10^(-3)mol·L^(-1),while the rinse of pH 9,I=10^(-1)mol·L^(-1)solution could remove most of the residual bacteria.This work not only enables controlled adsorption of proteins with different isoelectric points but also ensures that the surface of the coating is minimized from bacterial contamination.
文摘Leaf acid phosphatase (APase) activities of 274 soybean genotypes were surveyed under field conditions with two levels of P supplies, and a nutrient solution culture experiment with eight selected genotypes was subsequently conducted under greenhouse conditions to further characterize APase activity and its isoform expression induced by P starvation. Results from the field experiment showed that there was a great genotypic variation for leaf APase activity among the tested soybean genotypes from different origins, and APase activity in many of the tested genotypes (about 60%) was generally increased in the treatment without P fertilizer addition. Results from the nutrient solution culture experiment showed that APase activity in all the eight tested genotypes was generally enhanced by P starvation. Six isoforms of APases were detected in isoelectric focusing gels with samples from both young and old leaves. The activity of all the six isoforms was increased by P starvation, but no new APase isoform was induced. Our results suggest that leaf APase activity could serve as an enzymatic indicator of P starvation for soybean; the increase in leaf APase activity under low P stress was mainly caused by the increase in the activity of existing isoforms but not by the induction of new isoforms.
文摘The flotation behavior of Xixia andalusite was studied with different collectors.The tests were conducted with a pure andalusite sample in micro-flotation cell and then with an ore sample in a mechanical flotation cell.The surface charge was measured on pure andalusite sample and the isoelectric point（IEP） was found to be pH 5.2.Andalusite is floated with an amine collector above IEP where mineral surface is negatively charged.In contrast,an alkyl sulfonate collector（sodium dodecyl benzene sulfonate） is effective in the pH range where andalusite surface is positively charged.Furthermore,andalusite is floated with oleate in neutral and mildly alkaline pH values.55.3% Al2O3 is produced with 75.6% andalusite recovery when using the alkyl benzene sulfonate collector.Starch is found to be an effective depressant for gangue minerals in alkyl benzene sulfonate flotation.Moreover,slimes are found to have an adverse effect on the flotation of andalusite.Therefore,pretreatment by desliming and pre-float（to remove carbonaceous species） prior to andalusite flotation is necessary.
文摘等电聚焦(isoelectric focusing,简称IFF)也称等电点分离。自1960年代初,瑞典学者首次合成两性载体(商品名称有Ampholine和Pharmalyte等)并成功地用于蛋白质分离以来,这项技术得以迅速发展和应用。由于其分辨力高,可用于混合物的分离或鉴定,国外已应用此项技术对近交系动物进行生化标志基因监测。我们采用本实验室建立的聚丙烯酰胺凝胶等电聚焦技术对近交系小鼠SMMC/B的Hb基因位点进行遗传关系分析,并与常规聚丙烯酰胺凝胶电泳(polyacrylamide gel electrophoresis,PAGE)作分辨力比较。
基金the NSFC (No. 29775014) and Chinese Health Committee (98-2-334).
文摘A novel method is developed for electro-focusing and moving neutralization reaction boundary (MNRB) created with HCl and NaOH. The optimized conditions are screened out. By using this method, the experiments are performed on MNRB formed with HCl and NaOH in agarose gel. The experiments are quantitatively in coincidence with the predictions with the theory of moving chemical reaction boundary (MCRB).
文摘The stability of aqueous nano alumina powder suspensions with and without dispersant tri-ammonium citrate (TAC) was investigated by measuring zeta potential at different pH values. The isoelectric point (IEP) of alumina powder shifts towards more acidic pH range by adding TAC dispersant. The results illustrate that adsorption of TAC on alumina powder surface existed in the aqueous suspension, which leads to a high stability of the suspension.
文摘Maximum lignocellulose yield of biomass sorghum [Sorghum bicolor L. (Moench.)] is hampered by complex biological phenomena related to rotation, nitrogen (N) fertilization, soil tillage, and excessive biomass removal. The biochemical basis of the effects of agronomic practices on sorghum production was studied by the enzymology of the active peroxidase (EC 1.11.1.7) isoenzymes that synthesize lignin. All studied practices altered the peroxidase pI values. Control sorghum without rotation and without N fertilization had the most inhibited peroxidase with very low maximum velocity (Vmax) value (3.10 mmol·min﹣1), and very low lignin (857 kg·ha﹣1) yield, which could decrease soil organic carbon possibly leading to adverse changes in soil chemistry. Corn-sorghum rotations with and without N fertilization increased the Vmax values of peroxidase and lignin and cellulose yields. Rotated sorghum subjected to 50% residue return (the percentage of crop residue was returned to the plot immediately after grinding at harvest) and 280 kg·ha﹣1 N fertilization possessed very active peroxidase (Vmax value 66.4 mmole·min﹣1) and the highest lignin (1387 kg·ha﹣1) yield. The 25% residue return rate without N fertilization induced high lignin (1125 kg·ha﹣1) and cellulose (11,961 kg·ha﹣1) but the 25% residue return rate with 280 kg·ha﹣1 N fertilization induced lower lignin (1046 kg·ha﹣1) yield. Continuously cropped sorghum treated with 336 kg·N·ha﹣1 produced active peroxidase that shared competitive inhibition relationship with the peroxidase of the 84 kg·N·ha﹣1 treatment. Ridge tillage combined with 280 kg·ha﹣1 N fertilization under continuous sorghum resulted in inhibited peroxidase possessing low Vmax value (13.0 μmole·min﹣1). Changing to conventional tillage combined with 280 kg·ha﹣1 N fertilization relieved the inhibition and increased the Vmax value to 23.7 mmol·min﹣1. These biological anomalies of sorghum cell wall related to agronomic practices originated from doubly inhibited sorghum peroxidases. This understanding may guide the choice of sustainable agronomic practices for maximizing lignocellulose yields for the bioenergy industry while protecting the environment.
文摘The thiol components of the nonhistone proteins prepared from isolated nuclei from rat liver, regenerating liver and hepatoma 223 cells have been investigated after reaction with radio labelled N-ethylmaleimide and 5-5’-dithiobis-(2-nitrobenzoic acid) (DTNB). The labelled adducts formed were examined by isoelectric focusing analysis in polyacrylamide gel and the distribution of the radiolabels within sliced portions of the gels determined. In the case of the 14C labelled NEM adduct the label was found to be spread amongst numerous protein components within the gel however, in the case of the 35S labelled DTNB adducts, only a small proportion of the label was found in the protein material which was retained in the acidic isoelectric point (pI) region of the gel. The bulk of the 35S labelled adduct (56% - 60%) was found to have migrated into the anode solution (10 mM phosphoric acid). This could be adsorbed onto a hydrophobic resin (XAD2) resin and eluted with methanol. Gel filtration chromatographic analysis of this adduct material on BioGel P2, (exclusion limit 1500 daltons) showed low molecular weight components to be present. Slightly different patterns were obtained for these nuclei, each containing several 35S components with molecular weights greater than the Ellman reagent itself. These 35S labelled thiol components did not contain any protein, peptide or amino acid components indicating strongly that a novel species of thiols could be present in these nuclei bound within the non-histone protein matrices.
文摘The distribution of salivary acidic proline-rich proteins pheno-types was investigated by using the ultra-thin PAGIEF technique in 258 ChineseHan populations in Liaoning area. The gene frequencies were as follows: Pr^10.8101, Pr^20.1899; Db^+0.0416, Db^-0.9584; Pa^+0.1717, Pa^-0.8283; PIF^+0.6647, PIF^-0.3353. The observed numbers of the phenotypes are in good a-greement with the expected numbers under the Hardy-Weinberg equilibrium.The gene frequencies among the Chinese and other populations are compared.
