Albeck A, Kliper S
The Julius Spokojny Bioorganic Chemistry Laboratory, Department of Chemistry, Bar Ilan University, 52900, Ramat Gan, Israel.
Biochem J. 2000 Feb 15;346 Pt 1(Pt 1):71-6.
Erythro peptidyl epoxides are selective inactivators of cysteine proteases. The alkylation site, both on the enzyme papain and on the epoxide itself, was characterized. The inactivation of papain with the peptidyl epoxide erythro benzyloxycarbonyl-Phe-Ala-epoxide was followed by total hydrolysis by acid. Mass spectral analysis of the hydrolysate revealed, in addition to the expected amino acids, a unique signal of m/z 209 (MH(+)). Its high-resolution mass spectrum and daughter peak analysis correspond to the product of alkylation on cysteine and the expected fragmentation. A similar MS pattern was obtained for a synthetic model compound corresponding to the expected hydrolysis product. A (13)C NMR analysis of papain inactivated by a specifically (13)C-labelled peptidyl epoxide indicated that the alkylation of the enzyme's cysteine residue occurs on the primary carbon of the epoxide moiety.
赤型肽基环氧化物是半胱氨酸蛋白酶的选择性失活剂。对酶木瓜蛋白酶和环氧化物本身的烷基化位点进行了表征。用肽基环氧化物赤型苄氧羰基 - 苯丙氨酸 - 丙氨酸环氧化物使木瓜蛋白酶失活后，用酸进行完全水解。水解产物的质谱分析显示，除了预期的氨基酸外，还有一个质荷比为209（MH(+)）的独特信号。其高分辨率质谱和子峰分析对应于半胱氨酸上烷基化的产物以及预期的碎片。对于对应于预期水解产物的合成模型化合物，获得了类似的质谱图。用特异性(13)C标记的肽基环氧化物使木瓜蛋白酶失活后的(13)C NMR分析表明，酶的半胱氨酸残基的烷基化发生在环氧化物部分的伯碳上。
