Role of NAD⁺-Dependent Malate Dehydrogenase in the Metabolism of Methylomicrobium alcaliphilum 20Z and Methylosinus trichosporium OB3b.

ABSTRACT: We have expressed the l-malate dehydrogenase (MDH) genes from aerobic methanotrophs Methylomicrobium alcaliphilum 20Z and Methylosinus trichosporium OB3b as his-tagged proteins in Escherichia coli. The substrate specificities, enzymatic kinetics and oligomeric states of the MDHs have been characterized. Both MDHs were NAD⁺-specific and thermostable enzymes not affected by metal ions or various organic metabolites. The MDH from M. alcaliphilum 20Z was a homodimeric (2 × 35 kDa) enzyme displaying nearly equal reductive (malate formation) and oxidative (oxaloacetate formation) activities and higher affinity to malate (Km = 0.11 mM) than to oxaloacetate (Km = 0.34 mM). The MDH from M. trichosporium OB3b was homotetrameric (4 × 35 kDa), two-fold more active in the reaction of oxaloacetate reduc

SUBMITTER: Rozova ON 

PROVIDER: S-EPMC5023229 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature