In the present study, we developed a novel open-tubular capillary dectrochromatographic method using avidin-phospholipid vesicle complex as the stationary phase for chiral separation of mexiletine hydrochloride. The a...In the present study, we developed a novel open-tubular capillary dectrochromatographic method using avidin-phospholipid vesicle complex as the stationary phase for chiral separation of mexiletine hydrochloride. The avidin immobilized on the phospholipid vesicle consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine （DPPE） and L-u-phosphatidyl-L-serine （PS） （80：20, mg%） was coated in the capillary. The homogeneity and separation performance of the coating were evaluated in terms o f phospholipid vesicle characterization and the resolution of D,L-Tryptophan. As for mexiletine hydrochloride, four vital parameters affecting the separation efficiency of coating capillary, including buffer type, buffer pH, buffer concentration and the applied voltage, were studied in detail. Under the optimum conditions, the enantiomers could be separated well with good resolution. All the satisfactory results indicated that this method using avidin-phospholipid vesicle complex as the stationary phase was suitable and feasible, which had great potential in pharmaceutical separation Of enantiomers.展开更多
Avidin-liposome complex is a specific chiral selector used to separate the enantiomers of D,L-tryptophan,D,L-phenylthiohydantoin -serine（D,L-PTH-Ser）,D,L-phenylthiohydantoin-threonine（D,L-PTH-Thr） and R,S-pioglita...Avidin-liposome complex is a specific chiral selector used to separate the enantiomers of D,L-tryptophan,D,L-phenylthiohydantoin -serine（D,L-PTH-Ser）,D,L-phenylthiohydantoin-threonine（D,L-PTH-Thr） and R,S-pioglitazone hydrochloride in capillary electrochromatography（CEC）.The avidin is immobilized on the phospholipids coated in the capillary.The liposome used for the phospholipid coating contains l,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-（Cap biotinyl）（sodium salt） （Biotinyl-cap-DPPE）（16：0） and different proportions of L-α-phosphatidylserine（PS） in Tris（hydroxymethyl） aminomethane （Tris） buffer at pH 7.4.A good resolution and reproducibility was obtained by coating the capillary with Biotinyl-cap-DPPE/PS （80：20,mol%） followed by immobilization of 1 mg/mL of avidin solution in N-（2-hydroxyethyl） piperazine-N＇-（2-ethanesulfonic acid） （HEPES） buffer at pH 7.4.A comparative study of chiral separation efficiency with different capillary coating methods and preconditioning conditions was conducted.Finally,the electrochromatographic method was successfully used to separate enantiomers of pioglitazone hydrochloride.Therefore,coated CEC will be a promising tool for pharmaceutical enantiomers separation in new drug development.展开更多
AIM: To evaluate the influence of avidin chase on the side effects of radioimmunotherapy (RIT) in nude mice bearing human colon carcinoma and therapeutic outcome.METHODS: Purified anti-CEA monoclonal antibody (McAb)wa...AIM: To evaluate the influence of avidin chase on the side effects of radioimmunotherapy (RIT) in nude mice bearing human colon carcinoma and therapeutic outcome.METHODS: Purified anti-CEA monoclonal antibody (McAb)was biotinylated with NHS-biotin, and then radiolabeled with 188Re by the direct method. 188Re-labeledbiotinylated anti-CEA McAb (188Re-CEA McAb-Bt) was intravenously injected followed by intravenous injection of avidin after 24 h. SPECT imaging and biodistribution study were performed at 28-48 h after the injection of 188Re-CEA McAb-Bt. Three groups of nude mice subcutaneously grafted with human colon carcinoma were treated 7 d after the graft. Mice in the avidin chase group received intravenous injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg) followed by intravenous injection of cold avidin (80 μg) after 24 h. Mice in the control group (treated group without avidin chase) only received the injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg), another control group (non-treated group) only received 0.1 mL normal saline solution. Toxicity was evaluated on the basis of change of body weight and peripheral WBC counts, and therapy effects were determined by variation in tumor volume. Histological analysis of tumors was also performed.RESULTS: Avidin chase markedly accelerated the clearance of 188Re-CEA McAb-Bt from the blood and normal tissues. The tumor uptakes of 188Re-CEA Mc Ab-Bt at 28 h were 5.90 and 6.42% ID/g, respectively, in chase group and in non-chase group, while the tumor-to-background (T/NT) ratios were 3.19 and 0.56, respectively. The tumor uptake was slightly decreased by avidin chase, but the T/NT ratios were increased. In treated groups the growth rate of body weight and the number of WBC decreased after injection of 188Re-CEA McAb-Bt, and the WBC counts recovered earlier in the group with avidin chase than in the group without avidin chase. Compared to the nontreated group, treated groups with and without avidin chase showed significant anti-tumor effects.CONCLUSION: Avidin chase can effectively reduce the side effects of RIT, and improve therapeutic efficacy.展开更多
Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interacti...Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.展开更多
Objective:To labelavidin(Av)or streptavidin(SA)with 153 Sm by takingadvantageof thehighbindingaffin-ityof biotinto Av or SA.Methods:A biotinderivative(DTPA-biotin)wasradiolabelledwith 153 Sm andthenboundto Av or SA.Th...Objective:To labelavidin(Av)or streptavidin(SA)with 153 Sm by takingadvantageof thehighbindingaffin-ityof biotinto Av or SA.Methods:A biotinderivative(DTPA-biotin)wasradiolabelledwith 153 Sm andthenboundto Av or SA.Thein vivo kineticsandbiodistributionof 153 Sm-labeledAv,SA andDTPA-biotinwerestudiedinratsandmice.Results:153 Sm-Avwascharacterizedby rapidclearancefromthebloodwithhighliverandrenaluptake;153 Sm-SAwas clearedfromthebloodslowlywithhighretentionintheliver,spleenandkidney,whereas 153 Sm-DTPA-biotinmetabolismwas accelerated,anditsexcretionwasmainlythroughthekidney.Conclu sion:Thebiodistributiondifferenceof SAandAvmay providean experimentalbasisfor theselectionof differentcomponentsof avidin-biotinsystemin pretagetingradioim-munoimagingandradioimmunotherapy.展开更多
In this work an impedimetric immunosensor based on affinity immobilization method of a biotin labelled anti-human IgG antibody, used as a model system, was reported. The experimental procedure involves the growth of a...In this work an impedimetric immunosensor based on affinity immobilization method of a biotin labelled anti-human IgG antibody, used as a model system, was reported. The experimental procedure involves the growth of a self-assembled monolayer of a thiol (cysteamine) carrying terminal amine groups on gold electrodes. Glutarardehyde, a homobifunctional cross-linker, was used as a coupling reagent for the covalent linking of avidin to the amine groups of cysteamine. The attachment of the biotin labeled antibodies (anti-Human IgG) to the subsequent modified gold electrode was achieved by affinity interactions tacking advantage of the strong avidin-biotin bridge. The stepwise assembly process of the electrode was interrogated by means of cyclic voltammetry, electrochemical impedance spectroscopy and contact angle measurements. The response of the antibody modified electrode to their target antigens was investigated in the presence of BSA (bovin serum albumin) in order to alleviate non-specific adsorption problems. A proposed electrical model was used to analyse the experimental data. The resulting immunosensor has a linear dynamic range of 100 - 900 ng?ml<sup>–</sup>1 of antigen and a detection limit of 100 ng?ml<sup>–</sup>1.展开更多
1 Introduction X-ray diffraction is the major powerful method to resolve the problems on biological macromolecules in detail, but the large single crystals needed for analysis are usually.difficult to obtain. In contr...1 Introduction X-ray diffraction is the major powerful method to resolve the problems on biological macromolecules in detail, but the large single crystals needed for analysis are usually.difficult to obtain. In contrast to forming three-dimensional(3D) crystals, many proteins can form two-dimensional (2D) crystals easily. There have been several approaches to making 2D crystals. Lipid layer crystallization is a novel 2D crystallization method developed by Kornberg group. Some water-soluble proteins have been crystallized successfully by this method, and it can be possibly used to crystallize some intrinsic membrane proteins. The formed 2D crystals are展开更多
基金support of Professor Xuan Zhang’s research group,Laboratory of pharmaceutics,School of Pharmaceutical Sciences,Peking UniversityBeijing Kaiao Technology Development Co.,Ltd.
文摘In the present study, we developed a novel open-tubular capillary dectrochromatographic method using avidin-phospholipid vesicle complex as the stationary phase for chiral separation of mexiletine hydrochloride. The avidin immobilized on the phospholipid vesicle consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine （DPPE） and L-u-phosphatidyl-L-serine （PS） （80：20, mg%） was coated in the capillary. The homogeneity and separation performance of the coating were evaluated in terms o f phospholipid vesicle characterization and the resolution of D,L-Tryptophan. As for mexiletine hydrochloride, four vital parameters affecting the separation efficiency of coating capillary, including buffer type, buffer pH, buffer concentration and the applied voltage, were studied in detail. Under the optimum conditions, the enantiomers could be separated well with good resolution. All the satisfactory results indicated that this method using avidin-phospholipid vesicle complex as the stationary phase was suitable and feasible, which had great potential in pharmaceutical separation Of enantiomers.
文摘Avidin-liposome complex is a specific chiral selector used to separate the enantiomers of D,L-tryptophan,D,L-phenylthiohydantoin -serine（D,L-PTH-Ser）,D,L-phenylthiohydantoin-threonine（D,L-PTH-Thr） and R,S-pioglitazone hydrochloride in capillary electrochromatography（CEC）.The avidin is immobilized on the phospholipids coated in the capillary.The liposome used for the phospholipid coating contains l,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-（Cap biotinyl）（sodium salt） （Biotinyl-cap-DPPE）（16：0） and different proportions of L-α-phosphatidylserine（PS） in Tris（hydroxymethyl） aminomethane （Tris） buffer at pH 7.4.A good resolution and reproducibility was obtained by coating the capillary with Biotinyl-cap-DPPE/PS （80：20,mol%） followed by immobilization of 1 mg/mL of avidin solution in N-（2-hydroxyethyl） piperazine-N＇-（2-ethanesulfonic acid） （HEPES） buffer at pH 7.4.A comparative study of chiral separation efficiency with different capillary coating methods and preconditioning conditions was conducted.Finally,the electrochromatographic method was successfully used to separate enantiomers of pioglitazone hydrochloride.Therefore,coated CEC will be a promising tool for pharmaceutical enantiomers separation in new drug development.
基金Supported by the China Postdoctoral Science Foundation, No. 2003033345Medical Sciences and Technology Foundation of Guangdong Province, No.A2000389
文摘AIM: To evaluate the influence of avidin chase on the side effects of radioimmunotherapy (RIT) in nude mice bearing human colon carcinoma and therapeutic outcome.METHODS: Purified anti-CEA monoclonal antibody (McAb)was biotinylated with NHS-biotin, and then radiolabeled with 188Re by the direct method. 188Re-labeledbiotinylated anti-CEA McAb (188Re-CEA McAb-Bt) was intravenously injected followed by intravenous injection of avidin after 24 h. SPECT imaging and biodistribution study were performed at 28-48 h after the injection of 188Re-CEA McAb-Bt. Three groups of nude mice subcutaneously grafted with human colon carcinoma were treated 7 d after the graft. Mice in the avidin chase group received intravenous injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg) followed by intravenous injection of cold avidin (80 μg) after 24 h. Mice in the control group (treated group without avidin chase) only received the injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg), another control group (non-treated group) only received 0.1 mL normal saline solution. Toxicity was evaluated on the basis of change of body weight and peripheral WBC counts, and therapy effects were determined by variation in tumor volume. Histological analysis of tumors was also performed.RESULTS: Avidin chase markedly accelerated the clearance of 188Re-CEA McAb-Bt from the blood and normal tissues. The tumor uptakes of 188Re-CEA Mc Ab-Bt at 28 h were 5.90 and 6.42% ID/g, respectively, in chase group and in non-chase group, while the tumor-to-background (T/NT) ratios were 3.19 and 0.56, respectively. The tumor uptake was slightly decreased by avidin chase, but the T/NT ratios were increased. In treated groups the growth rate of body weight and the number of WBC decreased after injection of 188Re-CEA McAb-Bt, and the WBC counts recovered earlier in the group with avidin chase than in the group without avidin chase. Compared to the nontreated group, treated groups with and without avidin chase showed significant anti-tumor effects.CONCLUSION: Avidin chase can effectively reduce the side effects of RIT, and improve therapeutic efficacy.
基金the National Natural Science Foundation of China(Nos.21374058,21474060 and 21574078)the Ph.D. Programs Foundation of Ministry of Education of China(No 201331081100166)the Shanghai Rising-Star Program(No.16QA1401800)
文摘Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.
文摘Objective:To labelavidin(Av)or streptavidin(SA)with 153 Sm by takingadvantageof thehighbindingaffin-ityof biotinto Av or SA.Methods:A biotinderivative(DTPA-biotin)wasradiolabelledwith 153 Sm andthenboundto Av or SA.Thein vivo kineticsandbiodistributionof 153 Sm-labeledAv,SA andDTPA-biotinwerestudiedinratsandmice.Results:153 Sm-Avwascharacterizedby rapidclearancefromthebloodwithhighliverandrenaluptake;153 Sm-SAwas clearedfromthebloodslowlywithhighretentionintheliver,spleenandkidney,whereas 153 Sm-DTPA-biotinmetabolismwas accelerated,anditsexcretionwasmainlythroughthekidney.Conclu sion:Thebiodistributiondifferenceof SAandAvmay providean experimentalbasisfor theselectionof differentcomponentsof avidin-biotinsystemin pretagetingradioim-munoimagingandradioimmunotherapy.
文摘In this work an impedimetric immunosensor based on affinity immobilization method of a biotin labelled anti-human IgG antibody, used as a model system, was reported. The experimental procedure involves the growth of a self-assembled monolayer of a thiol (cysteamine) carrying terminal amine groups on gold electrodes. Glutarardehyde, a homobifunctional cross-linker, was used as a coupling reagent for the covalent linking of avidin to the amine groups of cysteamine. The attachment of the biotin labeled antibodies (anti-Human IgG) to the subsequent modified gold electrode was achieved by affinity interactions tacking advantage of the strong avidin-biotin bridge. The stepwise assembly process of the electrode was interrogated by means of cyclic voltammetry, electrochemical impedance spectroscopy and contact angle measurements. The response of the antibody modified electrode to their target antigens was investigated in the presence of BSA (bovin serum albumin) in order to alleviate non-specific adsorption problems. A proposed electrical model was used to analyse the experimental data. The resulting immunosensor has a linear dynamic range of 100 - 900 ng?ml<sup>–</sup>1 of antigen and a detection limit of 100 ng?ml<sup>–</sup>1.
基金Project supported by the National Natural Science Foundation of China.
文摘1 Introduction X-ray diffraction is the major powerful method to resolve the problems on biological macromolecules in detail, but the large single crystals needed for analysis are usually.difficult to obtain. In contrast to forming three-dimensional(3D) crystals, many proteins can form two-dimensional (2D) crystals easily. There have been several approaches to making 2D crystals. Lipid layer crystallization is a novel 2D crystallization method developed by Kornberg group. Some water-soluble proteins have been crystallized successfully by this method, and it can be possibly used to crystallize some intrinsic membrane proteins. The formed 2D crystals are
