{PDOC00062}
{PS00064; L_LDH}
{BEGIN}
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* L-lactate dehydrogenase active site *
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L-lactate dehydrogenase (EC 1.1.1.27) (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.
-Consensus pattern: [LIVMA]-G-[EQ]-H-G-[DN]-[ST]
[H is the active site residue]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: 1.
-Last update: November 1995 / Text revised.
[ 1] Abad-Zapatero C., Griffith J.P., Sussman J.L., Rossmann M.G.
J. Mol. Biol. 198:445-467(1987).
[ 2] Hendriks W., Mulders J.W.M., Bibby M.A., Slingsby C., Bloemendal H.,
de Jong W.W.
"Duck lens epsilon-crystallin and lactate dehydrogenase B4 are
identical: a single-copy gene product with two distinct functions."
Proc. Natl. Acad. Sci. U.S.A. 85:7114-7118(1988).
PubMed=3174623
[ 3] Lerch H.-P., Frank R., Collins J.
"Cloning, sequencing and expression of the L-2-hydroxyisocaproate
dehydrogenase-encoding gene of Lactobacillus confusus in Escherichia
coli."
Gene 83:263-270(1989).
PubMed=2684788
{END}