Kinetic analysis on the substrate specificity of 3-isopropylmalate dehydrogenase.
Substrate specificity of 3-isopropylmalate dehydrogenase is analyzed using a series of synthetic (2R,3S)-3-alkylmalates. Each analog with hydrogen, methyl, ethyl, isopropyl, isobutyl, tert-butyl, and isoamyl group on C-3 functions as a substrate, implying a broad substrate specificity of the enzyme toward alkylmalates. The incremental binding energy of the isopropyl group of 3-isopropylmalate to the enzyme is estimated to be 3.55 kcal/mol, the rather small value supporting the broad specificity. Although the enzyme shows a broad specificity toward the alkylmalates, it does not show activity with isocitrate which has a negatively charged carboxymethyl group instead of the alkyl groups.
Miyazaki
K
K
Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.
Kakinuma
K
K
Terasawa
H
H
Oshima
T
T
D050539:3-Isopropylmalate Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D007700:Kinetics; D013379:Substrate Specificity; D016963:Thermus thermophilus / Q000201:enzymology
D000429:Alcohol Oxidoreductases; D050539:3-Isopropylmalate Dehydrogenase