Efficient Substitution Reaction from Cysteine to the Serine Residue of Glycosylated Polypeptide: Repetitive Peptide Segment Ligation Strategy and the Synthesis of Glycosylated Tetracontapeptide Having Acid Labile Sialyl-T<sub>N</sub> Antigens
作者:Ryo Okamoto、Shingo Souma、Yasuhiro Kajihara
DOI:10.1021/jo8026164
日期:2009.3.20
This paper reports the synthesis of a 40-residue glycopeptide having two antigenic sialyl-TN (NeuAc-α-(2,6)-GalNAc-Thr) residues in the MUC1 sequence. This target glycopeptide is a tandem repeat form of 20-residue glycopeptides. For the synthesis of this large molecule, native chemical ligation (NCL) at the serine site was used (CysNCLSer). The concept of CysNCLSer relies on the following: (1) conventional
本文报道了40个残基的糖肽的合成,该肽在MUC1序列中具有两个抗原性唾液酸-T N(NeuAc-α-(2,6)-GalNAc-Thr)残基。该靶糖肽是20残基糖肽的串联重复形式。为了合成该大分子,使用了丝氨酸位点的天然化学连接(NCL)(Cys NCL Ser)。Cys NCL Ser的概念依赖于以下内容:(1)肽-α-硫酯与另一个肽段的半胱氨酸残基之间的常规NCL;(2)用于NCL的硫醇的甲基化;(3)半胱氨酸残基向丝氨酸残基的酸性CNBr转化,形成O-酯键;和(4)的直径: -到N-酰基转移以通过天然酰胺键偶联两个糖肽。为了合成具有酸不稳定糖部分的糖肽,通过固相糖肽合成来合成在N末端具有半胱氨酸残基的20残基糖肽-α-硫酯和20残基糖肽,然后通过Cys NCL Ser偶联。作为广泛研究的结果,发现用额外的酸(三氟乙酸)进行CNBr活化对于获得良好的反应性和产率至关重要,该条件提供了具有两个唾液酸-T