Kibirev V K, Romanova V P, Serebrianyĭ S B
Biokhimiia. 1983 Jun;48(6):937-43.
The action of thrombin on the esters, Tos-P2-Arg-OCH3 and Tos-P3-P2-Arg-OCH3, where P2 and P3 are the residues of L-, D- or N-methylamino acids, has been studied. The values of kcat and Km(app) under steady-state conditions at pH 8.5 have been determined. The results obtained and literature data suggest that one of the causes of the low catalytic potency of thrombin is a decrease in the hydrophobicity of the environment of Asp-102 located at the active site of the enzyme. Therefore thrombin can cleave only the peptides which hydrophobically shield Asp-102. The key role in this process may be played by the side chains of the amino acids at P2 and P9, thus suggesting the presence of a beta-turn in the P7-P4 region of the polypeptide substrates of thrombin.
已对凝血酶作用于酯类化合物Tos-P2-Arg-OCH3和Tos-P3-P2-Arg-OCH3的情况进行了研究，其中P2和P3是L-、D-或N-甲基氨基酸的残基。已测定了在pH 8.5的稳态条件下的kcat和Km(app)值。所获得的结果和文献数据表明，凝血酶催化效力较低的原因之一是位于酶活性位点的天冬氨酸-102周围环境疏水性的降低。因此，凝血酶只能切割那些通过疏水作用屏蔽天冬氨酸-102的肽段。在这个过程中，P2和P9位氨基酸的侧链可能起关键作用，从而表明在凝血酶多肽底物的P7-P4区域存在一个β-转角。
