FMN hydroxy acid dehydrogenase domain (IPR037396)

Short name: FMN_HAD

Overlapping homologous superfamilies

Domain relationships


A number of oxidoreductases that act on alpha-hydroxy acids and which are FMN-containing flavoproteins have been shown to be structurally related [PMID: 2324094, PMID: 2271624, PMID: 1939137, PMID: 15683236]; these enzymes are:

  • Lactate dehydrogenase (EC:, 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: ((S)-2-hydroxy-acid oxidase), a peroxisomal enzyme that catalyzes the conversion of glycolate and oxygen to glyoxylate and hydrogen peroxide.
  • Long chain alpha-hydroxy acid oxidase from rat (EC:, a peroxisomal enzyme.
  • Lactate 2-monooxygenase (EC: (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 alpha-carbon of the substrate producing a carbanion which can subsequently attach to the N5 atom of FMN. A conserved histidine has been shown [PMID: 2644287] to be involved in the removal of the proton. Three-dimensional structures of FMN-dependent alpha-hydroxy acid dehydrogenases show a common fold with a TIM barrel structure.

This entry represents the FMN hydroxy acid dehydrogenase domain.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles