A number of oxidoreductases that act on α-hydroxy acids and which are
FMN-containing flavoproteins have been shown [1,2,3,4] to be structurally
related; these enzymes are:
Lactate dehydrogenase (EC 220.127.116.11), which consists of a dehydrogenase
domain and a heme-binding domain called cytochrome b2 and which catalyzes
the conversion of lactate into pyruvate.
Glycolate oxidase (EC 18.104.22.168) ((S)-2-hydroxy-acid oxidase), a peroxisomal
enzyme that catalyzes the conversion of glycolate and oxygen to glyoxylate
and hydrogen peroxide.
Long chain α-hydroxy acid oxidase from rat (EC 22.214.171.124), a peroxisomal
Lactate 2-monooxygenase (EC 126.96.36.199) (lactate oxidase) from Mycobacterium
smegmatis, which catalyzes the conversion of lactate and oxygen to acetate,
carbon dioxide and water.
(S)-mandelate dehydrogenase from Pseudomonas putida (gene mdlB), which
catalyzes the reduction of (S)-mandelate to benzoylformate.
The first step in the reaction mechanism of these enzymes is the abstraction
of the proton from the α-carbon of the substrate producing a carbanion
which can subsequently attach to the N5 atom of FMN. A conserved histidine has
been shown  to be involved in the removal of the proton. We selected for a
signature pattern the region around this active site residue, which is highly
conserved and contains an arginine residue which is involved in substrate
binding. Three-dimensional structures of FMN-dependent α-hydroxy acid
dehydrogenases show a common fold with a TIM barrel structure (see
<PDB:1TB3>). We also developed a profile that covers the entire FMN hydroxy
acid dehydrogenase domain.
December 2007 / Text revised; profile added.
PROSITE methods (with tools and information) covered by this documentation:
Giegel D.A. Williams C.H. Jr. Massey V.
L-lactate 2-monooxygenase from Mycobacterium smegmatis. Cloning, nucleotide sequence, and primary structure homology within an enzyme family.
Mandelate pathway of Pseudomonas putida: sequence relationships involving mandelate racemase, (S)-mandelate dehydrogenase, and benzoylformate decarboxylase and expression of benzoylformate decarboxylase in Escherichia coli.
PROSITE is copyright. It is produced by the SIB Swiss Institute
Bioinformatics. There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to
or see: prosite_license.html.