caa a22 4500 378895974 CHVBK 20180305123506.0 cr unu---uuuuu 161128e20041201xx s 000 0 eng 10.1515/BC.2004.151 doi (NATIONALLICENCE)gruyter-10.1515/BC.2004.151 Replacement of the interchain disulfide bridge-forming amino acids A7 and B7 by glutamate impairs the structure and activity of insulin [Elektronische Daten] [Zhan-Yun Guo, Xiao-Yuan Jia, You-Min Feng] Insulin contains three disulfide bonds, one intrachain bond, A6-A11, and two interchain bonds, A7-B7 and A20-B19. Site-directed mutagenesis results (the two cysteine residues of disulfide A7-B7 were replaced by serine) showed that disulfide A7-B7 is crucial to both the structure and activity of insulin. However, chemical modification results showed that the insulin analogs still retained relatively high biological activity when A7Cys and B7Cys were modified by chemical groups with a negative charge. Did the negative charge of the modification groups restore the loss of activity and/or the disturbance of structure of these insulin analogs caused by deletion of disulfide A7-B7? To answer this question, an insulin analog with both A7Cys and B7Cys replaced by Glu, which has a long side-chain and a negative charge, was prepared by protein engineering, and its structure and activity were analyzed. Both the structure and activity of the present analog are very similar to that of the mutant with disulfide A7-B7 replaced by Ser, but significantly different from that of wild-type insulin. The present results suggest that removal of disulfide A7-B7 will result in serious loss of biological activity and the native conformation of insulin, even if the disulfide is replaced by residues with a negative charge. ©2004 by Walter de Gruyter Berlin New York Biochemistry nationallicence Molecular biology nationallicence Cellular biology nationallicence activity nationallicence disulfide bond nationallicence folding nationallicence insulin nationallicence structure nationallicence Guo Zhan-Yun Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, PR China aut Jia Xiao-Yuan Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, PR China aut Feng You-Min Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, PR China aut Biological Chemistry Walter de Gruyter 385/12(2004-12-01), 1171-1175 1431-6730 385:12<1171 2004 385 bchm https://doi.org/10.1515/BC.2004.151 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/BC.2004.151 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Guo Zhan-Yun Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, PR China aut NATIONALLICENCE 700 1- Jia Xiao-Yuan Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, PR China aut NATIONALLICENCE 700 1- Feng You-Min Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, PR China aut NATIONALLICENCE 773 0- Biological Chemistry Walter de Gruyter 385/12(2004-12-01), 1171-1175 1431-6730 385:12<1171 2004 385 bchm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter