Open AccessDXP Reductoisomerase: Reaction of the Substrate in Pieces Reveals a Catalytic Role for the Nonreacting Phosphodianion Group
Author(s) -
Svetlana A. Kholodar,
Andrew S. Murkin
Publication year - 2013
Publication title -
biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.43
H-Index - 253
eISSN - 1520-4995
pISSN - 0006-2960
DOI - 10.1021/bi400092n
Subject(s) - catalysis , chemistry , substrate (aquarium) , activator (genetics) , substrate specificity , stereochemistry , enzyme , organic chemistry , biochemistry , biology , ecology , gene
The role of the nonreacting phosphodianion group of 1-deoxy-d-xylulose-5-phosphate (DXP) in catalysis by DXP reductoisomerase (DXR) was investigated for the reaction of the "substrate in pieces". The truncated substrate 1-deoxy-l-erythrulose is converted by DXR to 2-C-methylglycerol with a kcat/Km that is 10(6)-fold lower than that for DXP. Phosphite dianion was found to be a nonessential activator, providing 3.2 kcal/mol of transition state stabilization for the truncated substrate. These results implicate a phosphate-driven conformational change involving loop closure over the DXR active site to generate an environment poised for catalysis.