SULFUR-SULFUR BRIDGING IN SOLID-PHASE PEPTIDE SYNTHESIS

二硫键是肽折叠的重要“标记”， 蛋白质，因为它们共价交联多肽的部分 在线性序列中分开但在三个中聚集在一起的链 尺寸.在本申请中，我们寻求建立在双胞胎 本实验室在温和化学方法固相 肽合成和硫化学发展一般新方法 用于在肽中产生硫-硫键。 用于硫-硫键形成的步骤将进行，同时进行硫-硫键形成。 肽保持锚定在聚合物支持物上，从而利用 伪稀释现象，有利于分子内环化。 这种方法需要良好的正交可去除半胱氨酸库 保护基团，以及释放未保护的单体的能力， 肽产物从支持物中分离，而不破坏或扰乱 二硫化物我们的多方面的方法将适用于最好的最近 锚定键的创新，温和的脱保护/裂解条件， 和聚合物载体来解决这一挑战性问题。两个预定 残基将被选择性地去封闭，然后进行小心的 共氧化或通过“定向”技术将它们连接为二硫化物。我们 将评估反应条件、树脂 替代水平和支持特性对产率和纯度的影响 单体材料。新方法将应用于生物活性 用一到三个二硫化物靶向分子，包括催产素， bactenecin、apamin和嗜中性粒细胞防御素。如果我们的合成 如果父结构成功，则将进行类比，其中一个或多个 二硫键被去除，环的大小减小或增加， 引入了构象刚性，并且有意地引入了二硫化物。 错配了类似物的二级和三级结构将是 以生物物理技术为特征，生物活动将 下定决心。最终，这种化学合成 合理设计的肽类似物可以提供更有效的，选择性的， 更持久的药物。

Disulfide bridges are significant "markers" for the folding of peptides and proteins, since they covalently cross-link portions of the polypeptide chain which are apart in the linear sequence but come together in three dimensions. In the present application, we seek to build on the twin expertises of this laboratory in mild chemical methods for solid-phase peptide synthesis and in sulfur chemistry to develop general new methods for the creation of sulfur-sulfur bonds in peptides. The steps for sulfur-sulfur bond formation will be carried out while a peptide remains anchored to a polymeric support, thereby taking advantage of the pseudo-dilution phenomenon which favors intramolecular cyclization. This approach requires a good repertoire of orthogonally removable cysteine protecting groups, and the capability to release unprotected monomeric peptide products from the support without breaking or scrambling the disulfides. Our multi-faceted approach will apply the best recent innovations in anchoring linkages, mild deprotection/cleavage conditions, and polymeric supports to this challenging problem. Two predetermined residues will be selectively deblocked, followed either by careful co-oxidation or by "directed" techniques to join them as a disulfide. We will assess the relative influence of reaction conditions, resin substitution level, and support characteristics on yield and purity of monomeric material. The new methods will be applied to biologically active target molecules with one to three disulfides, including oxytocin, bactenecin, apamin, and neutrophil defensins. If our syntheses of the parent structures are successful, analogies will be made where one or more disulfide is removed, ring size is decreased or increased, more conformational rigidity is introduced, and disulfides are intentionally mispaired. The secondary and tertiary structure of the analogues will be characterized by biophysical techniques, and the biological activities will be determined. Ultimately, the chemical synthesis of such rationally-designed peptide analogues may provide more potent, selective, and longer-lasting drugs.