Purification and characterization of NAD-dependent lactate dehydrogenase from Rhizopus oryzae
Journal
Food Chemistry
Journal Volume
41
Journal Issue
2
Pages
219-225
Date Issued
1991
Author(s)
Hang, Y.D.
Abstract
NAD-dependent lactate dehydrogenase (EC 1.1.1.27) of Rhizopus oryzae NRRL 395 was purified 175-fold with a yield of 63% by ammonium sulfate fractionation and Polybuffer exchanger 94 chromatofocusing. The purified enzyme had a specific activity of > 15 units per mg protein, and its sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern showed only one protein band. As estimated by gel filtration, the molecular weight of the native enzyme was 131 000 daltons, and as determined by SDS-PAGE, that of a subunit was 36 000 daltons. The purified enzyme was stable at room temperature. The optimal pH was about 7·5 and the isoelectric point (pI), as determined by chromatofocusing, was about 5·2. The Km values for NADH, pyruvate, and 2-oxobutyrate were 1·48, 6·40, and 54·4 × 10-4 M, respectively. Activity was inhibited by Cd2+, Fe2+, Hg2+, Pb2+ and Zn2+, but not by EDTA. © 1991.
SDGs
Type
journal article