OXIDATIVE FOLDING OF CYSTINE-RICH PEPTIDES VS REGIOSELECTIVE CYSTEINEPAIRING STRATEGIES

The methodology of regioselective cysteine pairings in synthetic multi ple-cystine peptides has progressed in the past years to an efficiency that allows for at least three specific inter- and intrachain disulfi de bridgings. Conformational studies on various multiple-cystine pepti des like hormones, protease inhibitors, and toxins revealed that these bioactive peptides, generated by posttranslational processing of prec ursor proteins, are folded into miniprotein-like compact globular stru ctures of remarkable stability. This strongly suggests protein domain or subdomain properties of these families of peptides, and thus suffic ient sequence-encoded information for correct oxidative refolding unde r appropriate experimental conditions. From intensive research on the mechanisms and pathways of oxidative refolding of proteins in vivo and in vitro, the efficient methods have emerged for simulating nature in the regeneration of native folds not only for intact proteins, but al so for protein domains and subdomains. In fact, the results obtained i n the oxidative folding of excised protein fragments and of relatively low mass products of posttranslational processings show that this pro cedure is indeed a simple way of preparing peptides with several disul fide bonds, if optimization of reaction conditions is performed in ter ms of redox buffer, temperature, and additives capable of disrupting a ggregates and of stabilizing nascent secondary structures. Moreover, w ith ina eased knowledge about stable, small natural cystine frameworks , their use instead of artificial templates should facilitate engineer ing of synthetic miniproteins with specific conformation and tailored functions. (C) 1996 John Wiley & Sons, Inc.