SULFUR-SULFUR BRIDGING IN SOLID-PHASE PEPTIDE SYNTHESIS

二硫键是多肽折叠的重要“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，但在三个序列中聚集在一起的链 尺寸。在本申请中，我们寻求在孪生兄弟的基础上 本实验室在固相温和化学方法方面的专家 多肽合成及在硫磺化学中开发通用新方法 在多肽中产生硫-硫键。 硫磺-硫键的形成步骤将在 多肽仍然锚定在聚合物载体上，从而利用 有利于分子内环化的伪稀释现象。 这种方法需要大量的正交性可移除半胱氨酸。 保护基团，以及释放未受保护的单体的能力 从支撑物中脱出的多肽产品不会破坏或争抢 二硫化物。我们的多方面方法将应用最近最好的 锚定连杆的创新，温和的解除保护/劈裂条件， 以及聚合物载体来解决这一具有挑战性的问题。两个预先确定的 残基将被选择性地解锁，然后是仔细的 共氧化或通过“定向”技术以二硫化物的形式加入它们。我们 将评估反应条件的相对影响，树脂 替代水平，以及对产量和纯度的支持特性 单体材料。新方法将应用于生物活性 含有一到三个二硫键的靶分子，包括催产素， 巴替尼丁、阿帕明和中性粒细胞防御素。如果我们的合成技术 父结构成功，将进行类比，其中一个或多个 二硫化物被去除，环尺寸减小或增加，更多 引入构象刚性，并有意引入二硫键 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的，生物活动将 要下定决心。归根结底，这种化学合成 合理设计的多肽类似物可能会提供更强大的，选择性的， 以及更持久的药物。

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.