利用三肽基对硝基苯胺底物对牛胰凝乳蛋白酶活性中心的研究。

Active centre studies on bovine pancreatic chymotrypsin with tripeptidyl-p-nitroanilide substrates.

作者信息

Tözsér J, Szabó G, Pozsgay M, Aurell L, Elödi P

出版信息

Acta Biochim Biophys Hung. 1986;21(4):335-48.

Abstract

The kinetic behaviour of bovine pancreatic chymotrypsin was studied with 22 N-protected and 17 N-unprotected tripeptidyl-p-nitroanilide substrates. The contribution of the individual side chains to the kinetic parameters were calculated by regression analysis. At subsite P1 (notation of Schechter and Berger, 1967, Biochem. Biophys. Res. Commun. 27, 157) Tyr seems to be better than Phe and Trp, concerning kcat values. At P2 subsite the best KM values were obtained with Gly and Ser, whereas the hydrophobicity of P2 subsite appears to be necessary for efficient catalytic activity. At P3 mainly polar amino acids, both with D and L configuration, were tested. They improve the solubility of substrates in aqueous medium, as well as the kinetic parameters. Suc(OMe) and Suc protecting groups at P4 increase significantly the catalytic activity compared to the aromatic ones. The obtained data were compared to the known substrate binding site of bovine pancreatic chymotrypsin.

摘要

使用22种N-保护和17种N-未保护的三肽基对硝基苯胺底物研究了牛胰凝乳蛋白酶的动力学行为。通过回归分析计算了各个侧链对动力学参数的贡献。在P1亚位点（Schechter和Berger，1967年，生物化学与生物物理研究通讯，27卷，第157页），就kcat值而言，酪氨酸似乎比苯丙氨酸和色氨酸更优。在P2亚位点，甘氨酸和丝氨酸获得了最佳的KM值，而P2亚位点的疏水性似乎是有效催化活性所必需的。在P3主要测试了具有D和L构型的极性氨基酸。它们提高了底物在水性介质中的溶解度以及动力学参数。与芳香族保护基团相比，P4处的琥珀酰（OMe）和琥珀酰保护基团显著提高了催化活性。将获得的数据与牛胰凝乳蛋白酶已知的底物结合位点进行了比较。