Affinity labelling of the allosteric site of the L‐lactate dehydrogenase of Lactobacillus casei

Abstract

Kinetic investigations employing the substrate analogues 2‐oxoglutarate and phospho(enol)pyruvate indicate that the allosteric L‐lactate dehydrogenase (EC 1.1.1.27) of Lactobacillus casei has a non‐catalytic pyruvate‐binding site to which, in addition to pyruvate, the allosteric effector fructose 1,6‐bisphosphate can also be bound. A modification using the 14C‐labelled substrate analogue 3‐bromopyruvate induces a loss of regulation by fructose 1,6‐bisphosphate. The histidine residue labelled by 3‐bromopyruvate is homologous to histidine‐188 which is part of the anion‐binding site of the non‐allosteric vertebrate l‐lactate dehydrogenases. Thus, the allosteric site of the allosteric l‐lactate dehydrogenases corresponds to the anion‐binding site of the non‐allosteric vertebrate enzymes. Copyright © 1983, Wiley Blackwell. All rights reserved