L-histidinol dehydrogenase, sourced from Escherichia coli, catalyses the last two steps of histidine biosynthesis: NAD dependent oxidation of L-histidinol to L-histinaldehyde and then to L-histidine. L-histidinol dehydrogenase is a homodimeric zinc metalloenzyme with one binding site per monomer. Each monomer contains four domains- the intertwined dimer possibly results from domain swapping. Two domains display a similar incomplete Rossmann fold, suggesting an ancient event of gene duplication.
Defined by 6 residues: GLN:A-259HIS:A-262GLU:A-326HIS:A-327ASP:A-360HIS:B-419