Purification and characterization of a new NAD super(+)-dependent enzyme, L-tartrate decarboxylase, from Pseudomonas) sp. group Ve-2

A new enzyme, L-tartrate decarboxylase, was found in cells of Pseudomonas sp. group Ve-2. The enzyme was purified to homogeneity and characterized. The enzyme requires K super(+), Mg super(2+), and NAD super(+) for L-tartrate decarboxylation. The dependence of the enzymatic decarboxylation on NAD super(+) suggests that the decarboxylation involves redox reactions of the substrate. The enzyme catalyzes NAD super(+)-linked oxidative decarboxylation of D-malate as well. The enzyme is composed of four subunits with identical molecular weight (M sub(r) 40,000). The apparent Michaelis constants for L-tartrate and NAD super(+) are 7.0 and 1.1 mM, respectively. The cofactor requirements and the physical properties of the enzyme were similar to those of L-tartrate dehydrogenase-D-malate dehydrogenase from Rhodopseudomanas sphaeroides), and tartrate dehydrogenase from P. putida .