title: Chemical modification of the hydroxylase of soluble methane monooxygenase gives one form of the protein with significantly increased thermostability and another that functions well in organic solvents.
abstract: Proteolysis of the hydroxylase component of soluble methane monooxygenase (MMO) with trypsin yielded a protein which retained 50% activity in a standard MMO assay. In an H2O2-driven assay, in which H2O2 replaced two of the protein components, NADH and O2 used in the standard assay, the proteolysed hydroxylase retained full activity for ethane, propane and propene, but had a 2-3-fold increase with methane as substrate. Several crosslinking reagents have been tested for their ability to stabilise the proteolysed form of the hydroxylase. Using polyoxyethylene bis(imidazolyl carbonyl) (M(r) 3350) as the crosslinking agent, increased thermostability of the hydroxylase was observed. Activated methoxypolyethylene glycol (M(r) 5000) was used to modify the hydroxylase which was now soluble in organic solvents as well as water and could be activated by H2O2. The glycol-modified hydroxylase functioned well in organic solvents in the catalysis of propene oxidation.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Jiang
authors.forename: H
authors.initials: H
authors.lastname: Dalton
mesh_terms: D004795:Enzyme Stability; D006358:Hot Temperature; D006899:Mixed Function Oxygenases / Q000737:chemistry*; D010105:Oxygenases / Q000737:chemistry*; D011092:Polyethylene Glycols; D012997:Solvents; D014357:Trypsin
chemical_list: D012997:Solvents; D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C021555:methane monooxygenase; D014357:Trypsin