Lactate dehydrogenases exist in four distinct enzyme classes. Two of them are cytochrome c-dependent enzymes, acting on either D-lactate (<db_xref db="EC" dbkey="1.1.2.4"/>)or L-lactate (<db_xref db="EC" dbkey="1.1.2.3"/>). The other two are NAD(P)- dependent enzymes, acting on either D-lactate (<db_xref db="EC" dbkey="1.1.1.28"/>) or L-lactate (<db_xref db="EC" dbkey="1.1.1.27"/>). This entry represents the cytochrome c-dependent L-lactate dehydrogenase, a member of the FMN-dependent alpha-hydroxy acid dehydrogenase family. It catalyses the oxidation of L-lactate to pyruvate [<cite idref="PUB00019771"/>]. The lld operon was previously named lct [<cite idref="PUB00053244"/>].