A module is called a co-＊∞-module if it is co-selfsmall and ∞-quasi-injective. The properties and characterizations are investigated. When a module U is a co-＊∞-module, the functor Hom RU（-,U）is exact in Copre...A module is called a co-＊∞-module if it is co-selfsmall and ∞-quasi-injective. The properties and characterizations are investigated. When a module U is a co-＊∞-module, the functor Hom RU（-,U）is exact in Copres∞（U）. A module U is a co-＊∞-module if and only if U is co-selfsmall and for any exact sequence 0→M→UI→N→0 with M∈Copres∞（U） and I is a set, N∈Copres∞（U） is equivalent to Ext1R（N,U）→Ext1R（UI,U） is a monomorphism if and only if U is co-selfsmall and for any exact sequence 0→L→M→N→0 with L, N∈Copres∞（U）, N∈Copres∞（U） is equivalent to the induced sequence 0→Δ（N）→Δ（M）→Δ（L）→0 which is exact if and only if U induces a duality ΔUS：⊥USCopres∞（U）：ΔRU. Moreover, U is a co-＊n-module if and only if U is a co-＊∞-module and Copres∞（U）=Copresn（U）.展开更多
Peptide mimics derived with close structure to peptide have vast utility because they are expected to interfere with biological targets while having superior drug-like properties if compared to peptides. In this work,...Peptide mimics derived with close structure to peptide have vast utility because they are expected to interfere with biological targets while having superior drug-like properties if compared to peptides. In this work, novel vinyl dipeptides which are different in a double bond between the α-carbon of peptide and C1 of its side chain. Added to that, suitable substituents were selected to harness drug-like properties. The compounds were found to have moderate activities when tested against MCF-7 breast cancer cell line. For instance, the adamantyl analogue 2-(benzoylamino)-3-(2-furyl)-N-(1-adamantyl) propenamide (1c) and the heterocyclic analogue 2-(Benzoylamino)-3-(2-furyl)-N-[2-(5-cyanothia-zol-2-yl)] propenamide (1o) exhibited inhibition potency at 27.4 and 37.8 μM, respectively.展开更多
Cordyceps sinensis(C.sinensis)is a widely used and highly valuable traditional Chinese medicine.Several dipeptides have been detected in C.sinensis,but current scientific knowledge of its chemical makeup remains limit...Cordyceps sinensis(C.sinensis)is a widely used and highly valuable traditional Chinese medicine.Several dipeptides have been detected in C.sinensis,but current scientific knowledge of its chemical makeup remains limited.In this study,an improved approach that integrates offline two-dimensional liquid chromatography(2D LC)separation,precursor ion list,library screening,and diagnostic ion filtering was established to systematically screen and characterize dipeptides in C.sinensis.Offline 2D LC integrating hydrophilic interaction LC and reverse phase separations was established to eliminate interference and identify the target dipeptides.A library containing the potential 400 dipeptides was created,and a precursor ion list with all theoretical precursor ions was adopted to trigger the MS/MS scan with high sensitivity.To identify dipeptides,the type and connection sequence of amino acids were determined according to the product ions.Ile and Leu residues were differentiated for the first time according to the characteristic ion at m/z 69.07.Ultimately,170 dipeptides were identified or tentatively characterized from C.sinensis,and most are reported for the first time in this species herein.In addition,the identified dipeptides were also applied for discrimination among the three Cordyceps species,and 11 markers were identified.The obtained results provide a deeper understanding of the chemical basis of C.sinensis.展开更多
For the first time, synthetic dipeptides were applied to the catalysis of asymmetric Reformatsky reaction. Review in this domain & factors influencing enantioselectivity were discussed.
A series of proline-based amino pyridine dipeptide organocatalysts was synthesized and applied in direct asymmetric intermolecular aldol reaction. These catalysts showed good solubility in organic solvents, good yiel...A series of proline-based amino pyridine dipeptide organocatalysts was synthesized and applied in direct asymmetric intermolecular aldol reaction. These catalysts showed good solubility in organic solvents, good yields （73%--97%） and enantioselectivitives（74%--94%）. Among them, dipeptide organocatalyst（2） was found to be the most efficient one for the asymmetric aldol reaction between cyclohexanone and 4-nitrobeznaldehyde. After optimizing the catalytic reaction conditions, we found that the catalyst showed high yield（97%）, enantioselectivity（e.e., up to 92%） and anti-diastcreoselectivity（up to 95：5） at mild room temperature without any additives.展开更多
We have developed a novel metal tag, bis(ethylenediamine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester (ECRS) for sensitive analysis of amino acids using high performance liquid chromatography/indu...We have developed a novel metal tag, bis(ethylenediamine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester (ECRS) for sensitive analysis of amino acids using high performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS). ECRS is a functional reagent, containing an ester group at one end that can be activated to bind to amino group and a chelated ruthenium at the other. The activated ester was reacted briefly with amino groups under weakly alkaline conditions. The ruthenium was detected sensitively by ICP-MS. ECRS was reacted with 17 proteinogenic amino acids in borate buffer. The derivatives were separated by reversed phase HPLC and identified by quadrupole-based ICP-MS. ECRS was suitable for speciation;low molecular weight compounds containing amino groups. We have thus established a quantitative analytical method for amino acids and dipeptides. The detection limits of branched amino acids (signal-to-noise ratio of 3) were 1.5 nmol·L-1 in the standard solution (100 amol per injection).展开更多
A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constant...A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.展开更多
On the basis of the Michael-addition mechanism of classical proteasome inhibitors, six dipeptide vinyl sulfonamide and dipeptide vinyl sulfonate derivatives were designed and synthesized. Moreover, an efficient method...On the basis of the Michael-addition mechanism of classical proteasome inhibitors, six dipeptide vinyl sulfonamide and dipeptide vinyl sulfonate derivatives were designed and synthesized. Moreover, an efficient method for the synthesis of g-amino vinyl sulfonamides, key intermediates to the target molecules, was developed via the Wittig-Horner reaction of peptide aldehyde with Wittig reagents derived from methanesulfonamides.展开更多
AIM: To assess the clinical and economical validity of glutamine dipeptide supplemented to parenteral nutrition (PN) in patients undergoing abdominal surgery. METHODS: A meta-analysis of all the relevant randomized co...AIM: To assess the clinical and economical validity of glutamine dipeptide supplemented to parenteral nutrition (PN) in patients undergoing abdominal surgery. METHODS: A meta-analysis of all the relevant randomized controlled trials (RCTs) was performed. The trials compared the standard PN and PN supplemented with glutamine dipeptide in abdominal surgery. RCTs were identified from the following electronic databases: the Cochrane Library, MEDLINE, EMBASE and ISI web of knowledge (SCI). The search was undertaken in April 2006. Literature references were checked by computer or hand at the same time. Clinical trials were extracted and evaluated by two reviewers independently. Statistical analysis was performed by RevMan4.2 software from Cochrane Collaboration. A P value of < 0.05 was considered statistically significant. RESULTS: Nine RCTs involving 373 patients were included. The combined results showed that glutamine dipeptide has a positive effect in improving postoperative cumulative nitrogen balance (weighted mean difference (WMD = 8.35, 95% CI [2.98, 13.71], P = 0.002), decreasing postoperative infectious morbidity (OR = 0.24, 95% CI [0.06, 0.93], P = 0.04), shortening the length of hospital stay (WMD= -3.55, 95% CI [-5.26, -1.84], P < 0.00001). No serious adverse effects were found. CONCLUSION: Postoperative PN supplemented with glutamine dipeptide is effective and safe to decrease the infectious rate, reduce the length of hospital stay and improve nitrogen balance in patients undergoing abdominal surgery. Further high quality trials in children and severe patients are required, and mortality and hospital cost should be considered in future RCTs with sufficient size and rigorous design.展开更多
基金The National Natural Science Foundation of China (No.10971024)Specialized Research Fund for the Doctoral Program of Higher Education (No.200802860024)
文摘A module is called a co-＊∞-module if it is co-selfsmall and ∞-quasi-injective. The properties and characterizations are investigated. When a module U is a co-＊∞-module, the functor Hom RU（-,U）is exact in Copres∞（U）. A module U is a co-＊∞-module if and only if U is co-selfsmall and for any exact sequence 0→M→UI→N→0 with M∈Copres∞（U） and I is a set, N∈Copres∞（U） is equivalent to Ext1R（N,U）→Ext1R（UI,U） is a monomorphism if and only if U is co-selfsmall and for any exact sequence 0→L→M→N→0 with L, N∈Copres∞（U）, N∈Copres∞（U） is equivalent to the induced sequence 0→Δ（N）→Δ（M）→Δ（L）→0 which is exact if and only if U induces a duality ΔUS：⊥USCopres∞（U）：ΔRU. Moreover, U is a co-＊n-module if and only if U is a co-＊∞-module and Copres∞（U）=Copresn（U）.
文摘Peptide mimics derived with close structure to peptide have vast utility because they are expected to interfere with biological targets while having superior drug-like properties if compared to peptides. In this work, novel vinyl dipeptides which are different in a double bond between the α-carbon of peptide and C1 of its side chain. Added to that, suitable substituents were selected to harness drug-like properties. The compounds were found to have moderate activities when tested against MCF-7 breast cancer cell line. For instance, the adamantyl analogue 2-(benzoylamino)-3-(2-furyl)-N-(1-adamantyl) propenamide (1c) and the heterocyclic analogue 2-(Benzoylamino)-3-(2-furyl)-N-[2-(5-cyanothia-zol-2-yl)] propenamide (1o) exhibited inhibition potency at 27.4 and 37.8 μM, respectively.
基金supported by the National Key R&D Program of China(Grant Nos.:2018YFC1707900,2019YFC1711000,and 2019YFC1711400)Key-Area Research and Development Program of Guangdong Province(Grant No.:2020B1111110007)+1 种基金the National Natural Science Foundation of China(Grant No.:82003938)Chief Scientist of Qi-Huang Project of National Traditional Chinese Medicine Inheritance and Innovation“One Hundred Million”Talent Project(2020).
文摘Cordyceps sinensis(C.sinensis)is a widely used and highly valuable traditional Chinese medicine.Several dipeptides have been detected in C.sinensis,but current scientific knowledge of its chemical makeup remains limited.In this study,an improved approach that integrates offline two-dimensional liquid chromatography(2D LC)separation,precursor ion list,library screening,and diagnostic ion filtering was established to systematically screen and characterize dipeptides in C.sinensis.Offline 2D LC integrating hydrophilic interaction LC and reverse phase separations was established to eliminate interference and identify the target dipeptides.A library containing the potential 400 dipeptides was created,and a precursor ion list with all theoretical precursor ions was adopted to trigger the MS/MS scan with high sensitivity.To identify dipeptides,the type and connection sequence of amino acids were determined according to the product ions.Ile and Leu residues were differentiated for the first time according to the characteristic ion at m/z 69.07.Ultimately,170 dipeptides were identified or tentatively characterized from C.sinensis,and most are reported for the first time in this species herein.In addition,the identified dipeptides were also applied for discrimination among the three Cordyceps species,and 11 markers were identified.The obtained results provide a deeper understanding of the chemical basis of C.sinensis.
文摘For the first time, synthetic dipeptides were applied to the catalysis of asymmetric Reformatsky reaction. Review in this domain & factors influencing enantioselectivity were discussed.
基金Supported by the National Natural Science Foundation of China(Nos.20802025 and 20082011)
文摘A series of proline-based amino pyridine dipeptide organocatalysts was synthesized and applied in direct asymmetric intermolecular aldol reaction. These catalysts showed good solubility in organic solvents, good yields （73%--97%） and enantioselectivitives（74%--94%）. Among them, dipeptide organocatalyst（2） was found to be the most efficient one for the asymmetric aldol reaction between cyclohexanone and 4-nitrobeznaldehyde. After optimizing the catalytic reaction conditions, we found that the catalyst showed high yield（97%）, enantioselectivity（e.e., up to 92%） and anti-diastcreoselectivity（up to 95：5） at mild room temperature without any additives.
文摘We have developed a novel metal tag, bis(ethylenediamine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester (ECRS) for sensitive analysis of amino acids using high performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS). ECRS is a functional reagent, containing an ester group at one end that can be activated to bind to amino group and a chelated ruthenium at the other. The activated ester was reacted briefly with amino groups under weakly alkaline conditions. The ruthenium was detected sensitively by ICP-MS. ECRS was reacted with 17 proteinogenic amino acids in borate buffer. The derivatives were separated by reversed phase HPLC and identified by quadrupole-based ICP-MS. ECRS was suitable for speciation;low molecular weight compounds containing amino groups. We have thus established a quantitative analytical method for amino acids and dipeptides. The detection limits of branched amino acids (signal-to-noise ratio of 3) were 1.5 nmol·L-1 in the standard solution (100 amol per injection).
文摘A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.
基金Natural Science Foundation of China for the financial support(Grant No.30772626)
文摘On the basis of the Michael-addition mechanism of classical proteasome inhibitors, six dipeptide vinyl sulfonamide and dipeptide vinyl sulfonate derivatives were designed and synthesized. Moreover, an efficient method for the synthesis of g-amino vinyl sulfonamides, key intermediates to the target molecules, was developed via the Wittig-Horner reaction of peptide aldehyde with Wittig reagents derived from methanesulfonamides.
文摘AIM: To assess the clinical and economical validity of glutamine dipeptide supplemented to parenteral nutrition (PN) in patients undergoing abdominal surgery. METHODS: A meta-analysis of all the relevant randomized controlled trials (RCTs) was performed. The trials compared the standard PN and PN supplemented with glutamine dipeptide in abdominal surgery. RCTs were identified from the following electronic databases: the Cochrane Library, MEDLINE, EMBASE and ISI web of knowledge (SCI). The search was undertaken in April 2006. Literature references were checked by computer or hand at the same time. Clinical trials were extracted and evaluated by two reviewers independently. Statistical analysis was performed by RevMan4.2 software from Cochrane Collaboration. A P value of < 0.05 was considered statistically significant. RESULTS: Nine RCTs involving 373 patients were included. The combined results showed that glutamine dipeptide has a positive effect in improving postoperative cumulative nitrogen balance (weighted mean difference (WMD = 8.35, 95% CI [2.98, 13.71], P = 0.002), decreasing postoperative infectious morbidity (OR = 0.24, 95% CI [0.06, 0.93], P = 0.04), shortening the length of hospital stay (WMD= -3.55, 95% CI [-5.26, -1.84], P < 0.00001). No serious adverse effects were found. CONCLUSION: Postoperative PN supplemented with glutamine dipeptide is effective and safe to decrease the infectious rate, reduce the length of hospital stay and improve nitrogen balance in patients undergoing abdominal surgery. Further high quality trials in children and severe patients are required, and mortality and hospital cost should be considered in future RCTs with sufficient size and rigorous design.
