Le Bras G, Garel J R
Laboratoire d'Enzymologie du CNRS, Gif-sur-Yvette, France.
FEMS Microbiol Lett. 1991 Mar 15;63(1):89-93. doi: 10.1016/0378-1097(91)90533-g.
The NAD-dependent D-lactate dehydrogenase from Lactobacillus bulgaricus has been purified to homogeneity. This enzyme was a dimer made of two identical chains of molecular mass 37,000. Saturation by either substrate was hyperbolic, with Km values of 50 microM for NADH and 1 mM for pyruvate. The specific activity was 2200 units/mg and was not affected by the presence of fructose-1,6-bisphosphate, Mn2+ ions, ATP or ADP. The amino-terminal sequence determined on 50 residues showed no significant homology with known lactate dehydrogenases, suggesting that the D-lactate dehydrogenase from L. bulgaricus could not be evolutionarily related to the family of NAD-dependent L-lactate dehydrogenases.
保加利亚乳杆菌中依赖NAD的D-乳酸脱氢酶已被纯化至同质。该酶是由两条分子量为37,000的相同链组成的二聚体。两种底物的饱和曲线均为双曲线，NADH的Km值为50微摩尔，丙酮酸的Km值为1毫摩尔。比活性为2200单位/毫克，不受1,6-二磷酸果糖、Mn2+离子、ATP或ADP的影响。对50个残基测定的氨基末端序列与已知的乳酸脱氢酶没有显著同源性，这表明保加利亚乳杆菌的D-乳酸脱氢酶在进化上与依赖NAD的L-乳酸脱氢酶家族无关。
