The primary structure of human IGF-I, except for the disulfide bond system, has been reported by Rinderknecht and Humbel. IGF-I afforded the corresponding characteristic peptide fragments on V8 protease digestion, which contained Cys6, Cys47, Cys48, and Cys52. Two possible fragments, Type I with Cys6–Cys47 and Cys48–Cys52 and Type II with Cys6–Cys48 and Cys47–Cys52 of h-IGF-I(4-9,47-53), were chemically synthesized. The disulfide bond system of IGF-I was unequivocally determined to be the Type-II form along with Cys18–Cys61. Interestingly, the Type-I system was included in the disulfide bond isomer produced as the main by-product in the refolding step on IGF-I synthesis by the recombinant DNA method.
除了二
硫键系统外,人类IGF-I的主要结构已由Rinderknecht和Humbel报道。在V8
蛋白酶消化过程中,IGF-I提供了相应的特征性肽片段,这些片段含有Cys6、Cys47、Cys48和Cys52。两种可能的片段,类型I含有Cys6–Cys47和Cys48–Cys52,类型II含有Cys6–Cys48和Cys47–Cys52的h-IGF-I(4-9,47-53),被
化学合成。IGF-I的二
硫键系统被明确确定为类型II形式,并伴随Cys18–Cys61。有趣的是,类型I系统包含在通过
重组DNA方法合成IGF-I的复性步骤中产生的主要副产品——二
硫键异构体中。