InterPro domain: IPR013118

Long-chain mannitol dehydrogenases are a group of secondary alcohol dehydrogenases that differ from other alcohol or polyol dehydrogenases in that they do not utilise Zn(2+) or other metal cofactors and do not contain a conserved catalytic tyrosine residue. The proteins in this family that have been studied are monomeric enzymes of ~54kDa and include:

• Mannitol-1-phosphate 5-dehydrogenase ( 1.1.1.17 ) [ 1 ]
• Mannitol 2-dehydrogenase ( 1.1.1.67 ) [ 2 ]
• D-arabinitol 4-dehydrogenase ( 1.1.1.11 ) [ 3 ]
• Altronate oxidoreductase ( 1.1.1.58 )
• D-mannonate oxidoreductase ( 1.1.1.57 )

These enzymes are mostly found in bacteria, though they are also present in some fungal species.

This entry represents the C-terminal substrate-binding domain of long-chain mannitol dehydrogenases. This domain is primarily alpha-helical in nature, being composed of eleven helices and a small beta hairpin [ 4 ]. Most of the residues implicated in substrate binding are located within this region, and a conserved lysine residue is thought to act as a proton acceptor during catalysis.

1. Molecular analysis of the mannitol operon of Clostridium acetobutylicum encoding a phosphotransferase system and a putative PTS-modulated regulator. Microbiology (Reading, Engl.) 147, 75-86
2. Cloning, nucleotide sequence and characterization of the mannitol dehydrogenase gene from Rhodobacter sphaeroides. J. Gen. Microbiol. 139, 2475-84
3. Genes for D-arabinitol and ribitol catabolism from Klebsiella pneumoniae. Microbiology (Reading, Engl.) 144 ( Pt 6), 1631-9
4. Crystal structure of Pseudomonas fluorescens mannitol 2-dehydrogenase binary and ternary complexes. Specificity and catalytic mechanism. J. Biol. Chem. 277, 43433-42