Direct identification of disulfide bond linkages in human insulin-like growth factor I (IGF-I) by chemical synthesis |
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| Authors: | M Iwai M Kobayashi K Tamura Y Ishii H Yamada M Niwa |
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| Institution: | Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., Osaka. |
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| Abstract: | 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 fragment 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, were 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. |
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