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用CD谱研究了厌氧条件下还原型胰岛素A,B链的相互作用。 结果表明,S-磺酸型胰岛素A,B链间及在过量DTT存在下的还原型胰岛素A,B链间基本无相互作用,分离链及混合链均表现为接近无序结构。而按巯基与磺酸基比为1.2和0.6加入DTT时,胰岛素入B链间存在相互作用,并导致α螺旋含量增加。在按巯基与磺酸基比为0.6加入DTT时,近紫外CD谱表明存在着二硫键的极快形成过程,而按巯基与磺酸基比为1.2加入DTT时,巯基基本不氧化,表明有序二级结构的增加与巯基氧化无直接关系,而仅为二条肽链间相互作用的表现。对按不同巯基与磺酸基比加入DTT时,DTT与S-磺酸型胰岛素链上的巯基交换存在二种方式,以及小环关闭的胰岛素A链对胰岛素链间的相互作用并无促进作用的可能性进行了讨论。
CD spectra were used to investigate the interaction of reduced insulin A and B chains under anaerobic conditions. The results showed that there was almost no interaction between the S-sulfonic acid insulin A and B chains and the reduced insulin A and B chains in the presence of excessive DTT, and both the isolated and the mixed chains showed nearly unordered structures. However, when DTT is added at a ratio of thiol to sulfonate of 1.2 and 0.6, there is an interaction between insulin into the B chain and an increase in the alpha helix content. The near-UV CD spectra of DTT at the thiol-to-sulfonate ratio of 0.6 indicate that there is an extremely fast formation of disulfide bonds, whereas thiol groups are not substantially oxidized at a DTT-to-sulfonate ratio of 1.2, indicating The increase of ordered secondary structure is not directly related to the sulfhydryl oxidation, but only the interaction between two peptide chains. There are two ways to exchange sulfhydryl groups on DTT and S-sulfonic acid type insulin chains when DTT is added to different sulfhydryl to sulfonic acid groups, and there is no way to promote the interaction between insulin chains through the small chain-closed insulin A chain The possibilities are discussed.