Oxidation of Some Alkanes and Trichloroethylene by H_2O_2/Hydroxylase System of Soluble Methane Monooxygenase from Methylocystis sp.M

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Soluble methane monooxygenase(sMMO)from Methylocystis sp.M, consisting of hydroxylase, reductase and component B, catalyzes O_2-and NADH-dependent monooxygenation. Although rapid NADH-coupled turnover normally requires all three components(the sMMO system), three less complex systems(combinations of hydroxylase, reductase, NADH and O_2, or hydroxylase and H_2O_2(H_2O_2/hydroxylase system))were also functional. Using propylene as a substrate in the H_2O_2/hydroxylase system, addition of component B at all concentrations led to a decrease in the reaction rate. In the sMMO system, almost stoichiometric concentrations of component B were required to maximize the enzyme reaction rate ; however, the reaction rate slowed when component B was present in concentrations greater than was required to saturate the initial hydroxylase. When straight C-chain alkanes longer than C4(n-butane and n-pentane)were used as substrates, the distribution profiles of the products from the two systems differed. When iso-pentane was a substrate, product distribution differed between the two systems with or without component B, suggesting that component B might change the structure of the substrate-binding site of hydroxylase in existence of reductase. The degration products and their proportions from a chlorinated alkene substrate(trichloroethylene)were identical when using the H_2O_2/hydroxylase and sMMO system.
社団法人日本生物工学会の論文
1998-03-25