title: Characteristic, activity and conformational studies of [A6-Ser, A11-Ser]-insulin.
abstract: Met-[A6-Ser, A11-Ser]-human proinsulin (Mut-HPI) was prepared in the same way as described previously for Met-human proinsulin (Met-HPI). After trypsin and carboxypeptidase B cleavage and DEAE-Sephadex A25 separation, Met-[A6-Ser, A11-Ser]-human insulin (Mut-HI) and Met-human insulin (Met-HI) were obtained. Their amino-acid compositions are in a good agreement with those expected. Mut-HI keeps full immuno activity, but loses almost all of its receptor binding activity with Met-HI as the control. Some physico-chemical behaviors of Mut-HI have changed to a certain extent. CD studies of mutant insulin demonstrates that the conformation of Met-HI is very similar to that of HI, while that of Mut-HI has altered slightly. The most important observation is that the binding ability of Mut-HI to the receptor has decreased abruptly. These results suggest that though the intra-A chain disulfide bond is deleted, the other two inter-chain disulfide bonds are still correctly paired, and that the intra-A chain disulfide bond is essential for insulin displaying its biological activity.
authors.affiliation: National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Dai
authors.forename: J G
authors.initials: JG
authors.lastname: Tang
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002942:Circular Dichroism; D006801:Humans; D007328:Insulin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D011384:Proinsulin / Q000378:metabolism; D011487:Protein Conformation; D011972:Receptor, Insulin / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D012694:Serine
chemical_list: D000596:Amino Acids; D007328:Insulin; D011994:Recombinant Proteins; C101198:insulin, Ser(A6,A11)-; D012694:Serine; D011384:Proinsulin; D011972:Receptor, Insulin