Purification and Biochemical Characterization of Soluble Methane Monooxygenase Hydroxylase from Methylosinus trichosporium IMV 3011

Abstract

Methane monooxygenase hydroxylase was purified by chromatography and characterized by electrophoresis and spectroscopy. The molecular mass of hydroxylase was 201.3 KDa as determined by gel filtration, whereas the total molecular mass was 234 KDa as judged by SDS–PAGE. Structure study indicated that the enzyme is a homodimer structure, consisting of three subunits, designated α, β, and γ, with molecular masses of 58 KDa, 36 KDa, and 23 KDa respectively. IEF analysis indicated that the enzyme has a pI of 5.2. The UV–Vis spectrum of hydroxylase revealed an absorption peak near 281 nm and a weak shoulder peak around 395 nm–420 nm, and a fluorescence spectrum revealed an emission peak at 341.3 nm. Circular dichroism measurement indicated that hydroxylase mainly consists of α-helical regions. Finally, phylogenetic analysis indicated that this strain is very close to Methylosinus trichosporium OB3b.