Zhang Z, Zhao S, Deans-Zirattu S, Bai G, Lee E Y
Department of Biochemistry & Molecular Biology, University of Miami School of Medicine, FL 33101.
Mol Cell Biochem. 1993 Nov;127-128:113-9. doi: 10.1007/BF01076762.
We have generated site-directed mutants of the catalytic subunit of rabbit muscle ppase-1. Since it is known that ppase-1 and ppase-2A are highly susceptible to inactivation by sulfhydryl reagents, we have mutagenized the six cysteine residues conserved between these two enzymes to serines. The six mutants were purified to near homogeneity by affinity chromatography on inhibitor-2-Sepharose and characterized. All six exhibited enzymatic activity. These results indicate that the catalytic mechanism of ppase-1 is different from that of the protein tyrosine phosphatases which involve a cysteinyl phosphate intermediate.
我们已经构建了兔肌肉磷酸酶-1（ppase-1）催化亚基的定点突变体。由于已知ppase-1和ppase-2A对巯基试剂高度敏感而失活，我们已将这两种酶之间保守的六个半胱氨酸残基突变为丝氨酸。通过在抑制剂-2-琼脂糖上进行亲和层析，将这六个突变体纯化至近乎均一，并对其进行了表征。所有六个突变体均表现出酶活性。这些结果表明，ppase-1的催化机制不同于涉及半胱氨酰磷酸中间体的蛋白质酪氨酸磷酸酶的催化机制。
