CHEMICAL MECHANISM OF BETA-GLUCOSIDASE FROM TRICHODERMA-REESEI QM-9414 - PH-DEPENDENCE OF KINETIC-PARAMETERS

被引：8

作者：

DELAMATA, I ^{[1
]}

ESTRADA, P ^{[1
]}

MACARRON, R ^{[1
]}

DOMINGUEZ, JM ^{[1
]}

CASTILLON, MP ^{[1
]}

ACEBAL, C ^{[1
]}

机构：

[1] UNIV COMPLUTENSE,FAC QUIM,DEPT BIOQUIM & BIOL MOLEC 1,E-28040 MADRID,SPAIN

来源：

BIOCHEMICAL JOURNAL | 1992年 / 283卷

关键词：

D O I：

10.1042/bj2830679

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The variation of kinetic parameters of beta-glucosidase from Trichoderma reesei QM 9414 with pH was used to gain information about the chemical mechanism of the reaction catalysed by this enzyme. The pH-dependence of V(max.) and V(max.)/K(m) for p-nitrophenyl beta-D-glucopyranoside showed that a group with a pK value of 4.3 must be unprotonated and a group with a pK value of 5.9 must be protonated for activity. Temperature and solvent-perturbation studies indicated that these groups are a histidine residue and a carboxy group respectively. Profiles of pK(i) for maltose as competitive inhibitor showed that binding is prevented when a group on the enzyme with a pK value of 4.5 becomes protonated.

引用

页码：679 / 682

页数：4

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