1. Kinetic data concerning the substrate and product inhibition by pyruvate and L-lactate have been obtained with the Md and Hd fractions separated from crystalline rabbit muscle lactic dehydrogenase. 2. The studies indicate that the product inhibition by L-lactate or by pyruvate is predominantly noncompetitive for both the Mq and Hq isozymes. Ki values for product inhibition by L-lactate were ...

In vitro reconstruction of the L-lactate/pyruvate shuttle has been performed, which allows NADH oxidation outside rat heart mitochondria. Such a shuttle occurs due to the combined action of the novel mitochondrial L-lactate/pyruvate antiporter, which differs from the monocarboxylate carrier, and the mitochondrial L-lactate dehydrogenase. The rate of L-lactate/pyruvate antiport proved to regulat...

Studies on the mechanism of substrate interaction with rabbit muscle lactate dehydrogenase have recently been reported (1). These investigations, which were primarily kinetic in nature, indicated that nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide must add to the enzyme before the binding of substrates pyruvate and L-lactate. It was also noted that ternary compl...

The demonstration that oxidation-reduction reactions mediated by the pyridine nucleotide coenzymes occur with the transfer of hydrogen between substrate and coenzyme (1) has led to the use of hydrogen isotopes to measure the occurrence of the specific coupling of reactions in the intact cell and organism (2-4). Several problems associated with the cellular organization and integration of the fe...

Using a DNA microarray, we found that expression of the genes related to lactate metabolism was upregulated in a lactate-producing recombinant Saccharomyces cerevisiae strain. Disruption of the CYB2 gene encoding L-lactate dehydrogenase improved the L-lactate production by S. cerevisiae under low pH condition.

Previous results indicated poor sugar consumption and early inhibition of metabolism and growth when Clostridium cellulolyticum was cultured on medium containing cellobiose and yeast extract. Changing from complex medium to a synthetic medium had a strong effect on (i) the specific cellobiose consumption, which was increased threefold; and (ii) the electron flow, since the NADH/NAD+ ratios rang...