Hellman U, Wernstedt C, Cazzulo J J
Ludwig Institute for Cancer Research, Uppsala Branch, Sweden.
Mol Biochem Parasitol. 1991 Jan;44(1):15-21. doi: 10.1016/0166-6851(91)90216-s.
The major cysteine proteinase (cruzipain) purified from Trypanosoma cruzi epimastigotes catalyzes its own degradation in the presence of beta-mercaptoethanol, at 56 degrees C and pH 6. The reaction is affected by the same inhibitors which inhibit the azocaseinase activity, and yields a major 25-kDa fragment, which contains carbohydrate, few, if any, aromatic amino acids, and presents a proline-rich N-terminus (GPGPXPEP...), in addition to a number of small peptides, which can be isolated by reversed-phase HPLC, but are lost during electrophoresis. The results, together with recently published evidence of Mottram et al. and Eakin et al., are compatible with a structure for cruzipain consisting of a conventional cysteine proteinase moiety, linked to a long C-terminal extension including the 25-kDa fragment, which would contain a high proportion of the carbohydrate and the proline residues present in the original 60-kDa molecule.
从克氏锥虫前鞭毛体中纯化得到的主要半胱氨酸蛋白酶（克氏锥虫蛋白酶），在β-巯基乙醇存在的情况下，于56℃和pH 6时会催化自身降解。该反应受到抑制偶氮酪蛋白酶活性的相同抑制剂的影响，并产生一个主要的25 kDa片段，该片段含有碳水化合物，几乎没有芳香族氨基酸，并且除了一些小肽外，其N端富含脯氨酸（GPGPXPEP...），这些小肽可通过反相高效液相色谱法分离，但在电泳过程中会丢失。这些结果，连同Mottram等人和Eakin等人最近发表的证据，与克氏锥虫蛋白酶的结构相一致，该结构由一个传统的半胱氨酸蛋白酶部分组成，与一个长的C端延伸部分相连，该延伸部分包括25 kDa片段，其中将含有原始60 kDa分子中高比例的碳水化合物和脯氨酸残基。
