Alves L C, Almeida P C, Franzoni L, Juliano L, Juliano M A
Escola Paulista de Medicina, São Paulo, Brazil.
Pept Res. 1996 Mar-Apr;9(2):92-6.
We report an improved procedure for the synthesis of fully protected aminoacyl 7-amino-4-methylcoumarin amide (MCA) employing the phosphorous oxychloride anhydride method. Seven Boc-X-MCA [where X = Arg(NG Tos), Cys(S-Bzl), Thr(O-Bzl), Ser(O-Bzl), Phe, Leu and Gly] and Z-Tyr(O-Me) were synthesized using this procedure, with yields ranging from 50% to 75%. These aminoacyl-MCA derivatives were employed for the synthesis of epsilon-NH2-caproyl-Leu-X-MCA, a fluorescent peptide series, which were assayed as papain substrates. All of them were completely hydrolyzed by papain, indicating that all of the Boc-X-MCA derivatives obtained were practically free of racemization. Since epsilon-NH2-Caproyl-Leu-(S-Bzl)Cys-MCA is very susceptible to hydrolysis by papain, quite resistant to hydrolysis by chymotrypsin and not hydrolyzed by trypsin, it is recommended for assays of thiol-proteinases in which specificity is required.
我们报道了一种采用三氯氧磷酸酐法合成完全保护的氨酰基7-氨基-4-甲基香豆素酰胺（MCA）的改进方法。使用该方法合成了七种Boc-X-MCA [其中X = Arg(NG Tos)、Cys(S-Bzl)、Thr(O-Bzl)、Ser(O-Bzl)、Phe、Leu和Gly] 以及Z-Tyr(O-Me)，产率在50%至75%之间。这些氨酰基-MCA衍生物用于合成荧光肽系列ε-NH2-己酰基-Leu-X-MCA，并作为木瓜蛋白酶底物进行测定。所有这些衍生物都被木瓜蛋白酶完全水解，这表明所得到的所有Boc-X-MCA衍生物实际上没有消旋化。由于ε-NH2-己酰基-Leu-(S-Bzl)Cys-MCA极易被木瓜蛋白酶水解，对胰凝乳蛋白酶水解相当抗性且不被胰蛋白酶水解，因此推荐用于需要特异性的巯基蛋白酶的测定。
