Facile peptide thioester synthesis via solution-phase tosylamide preparation

Preparation of peptide thioester is essential for native chemical ligation and block condensation. Our novel methodology involves conversion of the carboxylic acid of a peptide into a thioester using p-toluenesulfonyl isocyanate, followed by alkylation, then thiol substitution. Our methodology can also be used for the preparation of glycopeptide thioesters. Furthermore, it is possible to carry out the reaction as a sequential peptide chemical ligation.     

FAB MS of Permethylated L-β-Aspartamido-Carbohydrates

ＦＡＢＭＳｏｆＰｅｒｍｅｔｈｙｌａｔｅｄＬ┐β┐Ａｓｐａｒｔａｍｉｄｏ┐ＣａｒｂｏｈｙｄｒａｔｅｓＷＡＮＧＴｓｏｎｇ－ｈｕｉ＊（ＤｅｐａｒｔｍｅｎｔｏｆＩｎｓｔｒｕｍｅｎｔａｌＡｎａｌｙｓｉｓ，ＩｎｓｔｉｔｕｔｅｏｆＦｏｒｅｎｓｉｃＳｃｉｅｎｃｅ，Ｂ...     

Synthesis of Heavily Glycosylated Peptide αThioester

Erythropoietin (EPO) needs to be heavily glycosylated to exhibit its bioactivity in vivo. In order to synthesize heavily glycosylated EPO analogues, corresponding glycosylated peptide ^αthioesters are essential to prepare glycosylated whole EPO peptide backbones through native chemical ligation. After construction of the peptide ^αthioester corresponding to the 1–32 amino acid sequence in EPO, we aimed to incorporate three complex-type biantennary sialyloligosaccharides to this peptide ^αthioester by the haloacetamide method. The reaction afforded the desired heavily glycosylated peptide ^αthioester.