1h4i

Publication Abstract from PubMed

BACKGROUND: Methanol dehydrogenase (MDH) is a bacterial periplasmic quinoprotein; it has pyrrolo-quinoline quinone (PQQ) as its prosthetic group, requires Ca2+ for activity and uses cytochrome cL as its electron acceptor. Low-resolution structures of MDH have already been determined. RESULTS: The structure of the alpha 2 beta 2 tetramer of MDH from Methylobacterium extorquens has now been determined at 1.94 A with an R-factor of 19.85%. CONCLUSIONS: The alpha-subunit of MDH has an eight-fold radial symmetry, with its eight beta-sheets stabilized by a novel tryptophan docking motif. The PQQ in the active site is held in place by a coplanar tryptophan and by a novel disulphide ring formed between adjacent cysteines which are bonded by an unusual non-planar trans peptide bond. One of the carbonyl oxygens of PQQ is bonded to the Ca2+, probably facilitating attack on the substrate, and the other carbonyl oxygen is out of the plane of the ring, confirming the presence of the predicted free-radical semiquinone form of the prosthetic group.

The refined structure of the quinoprotein methanol dehydrogenase from Methylobacterium extorquens at 1.94 A.,Ghosh M, Anthony C, Harlos K, Goodwin MG, Blake C Structure. 1995 Feb 15;3(2):177-87. PMID:7735834^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.