Novel Techniques for the Synthesis and Coupling of Peptide Segments

这项研究是由有机合成化学项目资助的。正在开发合成自然产生的中链或长链多肽的新技术，这将使它们迅速以多克数量用于测试目的。基于碱和溶剂敏感氨基保护基团的新合成技术有望快速获得多克数量的短肽，并显着改进少量长肽的合成。合成100个或100个以上氨基酸单元的长肽链的方法与采用分步方法的方法相比，具有显著的优势。将研究组装适当链段的三种方法：(A)Fmoc/多胺溶液技术，(B)两种聚合物(“逆Merrifield”)方法和(C)标准Merrifield固相法。在这三种方法中，将研究新发现的Fmoc氨基酸氟化物作为快速、廉价偶联剂的适用性。这种试剂现在可用于除四种常见氨基酸以外的所有氨基酸。将开发适用于这四种化合物(Arg、Asn、Gln、His)的酸性氟化物试剂。为了便于固相合成，将研究两种特殊的树脂载体：(A)叔醇树脂，其应完全阻止由于在脱肽阶段形成二酮基哌嗪而导致的多肽从树脂中损失，特别是在C末端或倒数第二个氨基酸或甘氨酸的情况下，以及(B)树脂支承具有叔氨基醇功能的情况，该功能应用于催化第一个氨基酸的负载，从而促进从第一个氨基酸到最后一个氨基酸的完全在线自动合成。一旦有了快速、常规的合成受保护链段的方法，将研究溶液和固相法的链段偶联。将寻求一种新的方法来实现无外消旋链段偶联，该方法包括通过FM-bar或相关的酰胺保护剂来保护C-末端的酰胺键。用来研究这些技术应用的模型是一段19个单位的家蚕促胸腺激素原PTTH-II-(1-19)。

This research is being funded by the Organic Synthesis Chemistry Program. New techniques for the synthesis of naturally occurring medium or long chain peptides are being developed which will make them rapidly available in multi-gram quantities for testing purposes. New synthetic techniques based on base- and solvent-sensitive amino-protecting groups promise to make available quickly multi-gram quantities of shorter peptides and to markedly improve the synthesis of small quantities of longer peptides. Methods for the synthesis of long peptide chains of 100 or more amino acid units which involve the coupling of segments enjoy significant advantages over those involving stepwise approaches. Three methods for assembling the appropriate segments will be studied: (a) the FMOC/Polyamine solution technique, (b) the two polymer ("inverse merrifield") approach and (c) the standard Merrifield solid phase method. In all three approaches the applicability of newly-discovered FMOC amino acid fluorides as rapid-acting, inexpensive coupling agents will be studied. Such reagents are now available for all but four of the common amino acids. Synthesis of appropriate acid fluoride reagents for these four compounds (Arg, Asn, Gln, His) will be developed. To facilitate solid phase syntheses two special resin supports will be investigated: (a) tertiary alcohol resins which should completely inhibit loss of peptide from the resin due to diketopiperazine formation at the depeptide stage, especially in the case of C-terminal or penultimate proline or glycine and (b) resin supports bearing tertiary aminoalcohol functions which should serve to catalyse loading of the first amino acid and thereby promote complete on-line automated syntheses from the first to the last amino acid. Once rapid, routine methods for the synthesis of protected segments are available, both solution and solid phase methods of segment coupling will be examined. A novel method of effecting racemization-free segment coupling involving protection of the C-terminal amide bond by FM-bar or a related amide protectant will be pursued. The model chosen to study the application of these techniques is a 19-unit segment of a silkworm prothoracicotropic hormone, PTTH-II-(1-19).