PROSITE documentation PDOC00062 [for PROSITE entry PS00064]
L-lactate dehydrogenase active site


L-lactate dehydrogenase (EC (LDH) [1] catalyzes the reversible NAD-dependent interconversion of pyruvate to L-lactate. In vertebrate muscles and in lactic acid bacteria it represents the final step in anaerobic glycolysis. This tetrameric enzyme is present in prokaryotic and eukaryotic organisms. In vertebrates there are three isozymes of LDH: the M form (LDH-A), found predominantly in muscle tissues; the H form (LDH-B), found in heart muscle and the X form (LDH-C), found only in the spermatozoa of mammals and birds. In birds and crocodilian eye lenses, LDH-B serves as a structural protein and is known as epsilon-crystallin [2].

L-2-hydroxyisocaproate dehydrogenase (EC 1.1.1.-) (L-hicDH) [3] catalyzes the reversible and stereospecific interconversion between 2-ketocarboxylic acids and L-2-hydroxy-carboxylic acids. L-hicDH is evolutionary related to LDH's.

As a signature for LDH's we have selected a region that includes a conserved histidine which is essential to the catalytic mechanism.

Last update:

November 1995 / Text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

L_LDH, PS00064; L-lactate dehydrogenase active site  (PATTERN)


1AuthorsAbad-Zapatero C. Griffith J.P. Sussman J.L. Rossmann M.G.
SourceJ. Mol. Biol. 198:445-467(1987).

2AuthorsHendriks W. Mulders J.W.M. Bibby M.A. Slingsby C. Bloemendal H. de Jong W.W.
TitleDuck lens epsilon-crystallin and lactate dehydrogenase B4 are identical: a single-copy gene product with two distinct functions.
SourceProc. Natl. Acad. Sci. U.S.A. 85:7114-7118(1988).
PubMed ID3174623

3AuthorsLerch H.-P. Frank R. Collins J.
TitleCloning, sequencing and expression of the L-2-hydroxyisocaproate dehydrogenase-encoding gene of Lactobacillus confusus in Escherichia coli.
SourceGene 83:263-270(1989).
PubMed ID2684788

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