Collect. Czech. Chem. Commun. 1988, 53, 1857-1861

Interaction of lactate dehydrogenase isoenzymes with ligands

Jana Barthová, Jana Kučerová and Sylva Leblová

Department of Biochemistry, Charles University, 128 40 Prague 2


Isoenzymes of bovine lactate dehydrogenase (H4, H3M, and H2M2) were prepared by affinity chromatography on a 5'-AMP-Sepharose 4B column. The interaction of isoenzymes with two ligands, coenzyme NADH and the competitive inhibitor Cibacron Blue F3GA was followed by means of kinetic measurements and by affinity electrophoresis. The Michaelis constants of NADH were compared with the inhibition constants of Cibacron Blue and dissociation constants of enzyme-inhibitor complexes. It was found that the M subunit of lactate dehydrogenase exhibits always higher affinity both to NADH and Cibacron Blue in comparison to the H subunit. This finding corresponds to the physiological role of lactate dehydrogenase isoenzymes.