The mercaptomethyl group facilitates an efficient one-pot ligation at Xaa-Ser/Thr for (glyco)peptide synthesis.
The mercaptomethyl group facilitates an efficient one-pot ligation at Xaa-Ser/Thr for (glyco)peptide synthesis.
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DOI：
10.1002/anie.201000384
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发表时间：
2010-07
影响因子：
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通讯作者：
H. Hojo;Chinatsu Ozawa;H. Katayama;A. Ueki;Y. Nakahara;Y. Nakahara
中科院分区：
文献类型：
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作者：
H. Hojo;Chinatsu Ozawa;H. Katayama;A. Ueki;Y. Nakahara;Y. Nakahara
天然化学连接（NCL）方法通常用于（糖）蛋白的合成。[1]除了羧基组分的末端羧基被硫酯基团保护外，它在没有官能团保护的情况下有效地缩合肽段。因此，可以通过固相法或重组DNA技术容易地制备片段。最近，通过重组DNA技术制备肽硫酯也已通过内含肽技术实现。[2]NCL的主要问题是在连接位点需要半胱氨酸残基以实现化学选择性偶联。由于蛋白质中半胱氨酸残基的天然丰度低（1.5%），因此连接位点受到该问题的严重限制。因此，已经进行了许多努力来开发硫醇辅助基团以克服这种限制。[3]In初始研究[3a-d，f-i] α-氨基用于锚巯基辅助基团，其在连接后被裂解。然而，由于空间位阻，这种策略可能导致不完全连接，因此主要用于连接位点含有至少一个甘氨酸残基的情况。其他策略在侧链官能团处使用硫醇基团，其随后转化为蛋白质氨基酸形式。在这些策略中，连接似乎有效地进行，因为硫酯中间体中的酰基使用碳水化合物部分上的硫醇基团通过五元环、六元环或甚至更大元环转移到伯氨基。[3i这些策略还需要用于去除辅助基团的额外反应，这主要通过基于金属的还原进行。然而，当应用于具有各种官能团的肽的合成时，该反应可能不相容，
The native chemical ligation (NCL) method is generally used for the synthesis of (glyco) proteins.[1] It efficiently condenses peptide segments without the protection of functional groups, except for the terminal carboxyl group of the carboxyl component by the thioester group. Thus, the segments can be easily prepared by the solid-phase method or recombinant DNA technology. Recently, the preparation of peptide thioesters by the recombinant DNA technique has also been realized by intein technology.[2] The major problem in NCL is that a cysteine residue is required at the ligation site to achieve chemoselective coupling. Since the natural abundance of the cysteine residue in proteins is low (1.5%), the ligation site is severely limited by this problem. Thus, much effort has been made to develop thiol auxiliary groups to overcome this limitation.[3]In initial studies,[3a–d, f–i] the α-amino group was used to anchor thiol auxiliary groups, which were cleaved after the ligation. However, this strategy might lead to incomplete ligation as a result of steric hindrance, and thus has been mainly used where the ligation site contains at least one glycine residue. The other strategies used thiol groups at the side-chain functional groups, which were subsequently converted to proteinogenic amino acid forms. In these strategies the ligation seems to proceed efficiently, as the acyl group in the thioester intermediate is transferred to the primary amino group through five-, six-, or even larger-membered rings using the thiol group on carbohydrate moieties.[3i, m] These strategies also require additional reaction for the removal of auxiliary groups, which is mainly carried out by metal-based reduction. However, the reaction might not be compatible when applied to the synthesis of peptides having various functional groups,