title: Evidence for two histidine ligands at the diiron site of methane monooxygenase.
abstract: Circular dichroism spectroscopy has shown the hydroxylase component of methane monooxygenase to have a high helical content. The apoprotein has the same secondary structure as the holoenzyme. Chemical modification shows 12 histidines to be reactive with diethylpyrocarbonate in the holoenzyme, whereas 14 are reactive in the apoenzyme. Two histidine residues are implicated as iron ligands. Further chemical modification results suggest a cysteine residue is in close proximity to the diiron centre.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry, England.
authors.forename: D D
authors.initials: DD
authors.lastname: Smith
authors.forename: H
authors.initials: H
authors.lastname: Dalton
mesh_terms: D001051:Apoenzymes / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D004047:Diethyl Pyrocarbonate / Q000378:metabolism / Q000494:pharmacology; D006639:Histidine / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D008772:Methylococcaceae / Q000201:enzymology*; D010105:Oxygenases / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D013861:Thiocyanates / Q000494:pharmacology
chemical_list: D001051:Apoenzymes; D013861:Thiocyanates; D006639:Histidine; D007501:Iron; D010105:Oxygenases; C021555:methane monooxygenase; D003545:Cysteine; D004047:Diethyl Pyrocarbonate; C008658:2-nitro-5-thiocyanobenzoic acid