title: p-cresol methylhydroxylase from a denitrifying bacterium involved in anaerobic degradation of p-cresol.
abstract: A bacterium, strain PC-07, previously isolated as part of a coculture capable of growing on p-cresol under anaerobic conditions with nitrate as the acceptor was identified as an Achromobacter sp. The first enzyme of the pathway, p-cresol methylhydroxylase, which converts its substrate into p-hydroxybenzyl alcohol, was purified. The enzyme had an Mr of 130,000 and the spectrum of a flavocytochrome. It was composed of flavoprotein subunits of Mr 54,000 and cytochrome subunits of Mr 12,500. The midpoint redox potential of the cytochrome was 232 mV. The Km and kcat for p-cresol were 21 microM and 112 s-1 respectively, and the Km for phenazine methosulfate, the artificial acceptor used in the assays, was determined to be 1.7 mM. These properties place the enzyme in the same class as the p-cresol methylhydroxylases from aerobically isolated Pseudomonas spp.
authors.affiliation: Department of Biochemistry, University College of Wales, Aberystwyth, Dyfed, United Kingdom.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hopper
authors.forename: I D
authors.initials: ID
authors.lastname: Bossert
authors.forename: M E
authors.initials: ME
authors.lastname: Rhodes-Roberts
mesh_terms: D000421:Alcaligenes / Q000201:enzymology*; D000693:Anaerobiosis; D003408:Cresols / Q000378:metabolism*; D003580:Cytochromes / Q000378:metabolism; D005420:Flavoproteins / Q000378:metabolism; D007700:Kinetics; D006899:Mixed Function Oxygenases / Q000302:isolation & purification / Q000378:metabolism*; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003408:Cresols; D003580:Cytochromes; D005420:Flavoproteins; C032538:4-cresol; D006899:Mixed Function Oxygenases; C049502:4-cresol dehydrogenase (hydroxylating)