Thallium (III) trifluoroacetate, a mild oxidant with a soft-acid character, was found to cleave various S-protecting groups of cysteine in trifluoroacetic acid, with spontaneous formation of cystine. Except for unmasked Trp and Met, other amino acids, including His and Tyr, remained intact in the presence of this oxidant. The usefulness of this oxidant for intramolecular disulfide bond-forming reactions was demonstrated by direct conversion of three model S-protected cysteine-peptides into cystine-peptides, i.e., oxytocin, urotensin II and human calcitonin generelated peptide.
                                    研究发现,
三氟乙酸铊(III)是一种具有软酸性质的温和氧化剂,可裂解
三氟乙酸中半胱
氨酸的各种 S 保护基团,并自发形成胱
氨酸。除了未屏蔽的 Trp 和 Met 外,包括 His 和 Tyr 在内的其他
氨基酸在这种氧化剂的作用下保持完好无损。通过将三种受 S 保护的半胱
氨酸肽模型(即
催产素、尿促性素 II 和人类
降钙素生成肽)直接转化为胱
氨酸肽,证明了这种氧化剂在分子内二
硫键形成反应中的作用。