| 摘要 |
Prepn. of insulin comprises first condensing suitably protected amino acids to give a fragment contg. at least the 6-11 units of chain A in which NH2 COOH and/or OH are opt. protected. Cysteine gps. at 6 and 11 are protected by gps. R1 (aralkyl or arylcycloalkyl with is not >7C (cyclo)alkyl portion and is not >1 aryl on the C atom attached to mercapto S). The A-7 Cys residue is protected by acylaminomethyl (R2). Gps. R1 are then cleaved, with formation of a disulphide bridge, by iodine in a polyhalogenated aliphatic hydroxy or oxo cpd. (III). The fragment can then be extended at either end with suitable protected amino acids, and condensed with a fragment contg. the disulphide bridge between A-20 and B-19. If a B-7 Cys is present it is protected by R2. Where necessary chains A and B are completed, then the NH2, COOH and OH protecting gps. removed. before or after this A-7 and B-7 Cys are deprotected and the disulphide bridge formed by (opt. simultaneous) oxidation. Used specifically for human insulin. By using different Cys protectin gps. the disulphide bridges can be formed selectively at different points in the synthesis.
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