1h4i
From Proteopedia
METHYLOBACTERIUM EXTORQUENS METHANOL DEHYDROGENASE
Overview
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.
About this Structure
1H4I is a Protein complex structure of sequences from Methylobacterium extorquens. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Fri May 2 18:25:14 2008
