Purification and characterization of methyl chloride transferase: A novel halogenating enzyme

Methyl Chloride is biologically produced at an annual global emission rate of $5\times10\sp6$ tons. Production of this molecule is thought to be mostly biological in nature. The established route for production of halometabolites is the hydrogen peroxide-dependent halogenation mechanism common to haloperoxidase enzymes such as chloroperoxidase. No production of monohalomethanes can be detected by the haloperoxidase mechanism. The white rot fungus, Phellinus pomaceus has been known to produce methyl chloride in vivo. After determining appropriate growth conditions for optimal methyl chloride production, we have partially purified an enzyme from this fungus which produces methyl chloride. This enzyme utilizes S-adenosyl methionine (SAM) as a methyl donor in a methyl transferase reaction in which chloride, bromide and iodide are all methyl acceptors.A survey of marine algae detected in vivo methyl chloride production by 20 of 31 algae species collected. Subsequently, in vitro production of methyl iodide was studied in five of these species. In all species studied, the reaction occurred by the methylation route described in the fungus. The enzyme has been purified from one algae species, Endocladia muricata. The enzyme from this source has a Km for bromide of, 40 mMolar, for chloride, 4 mMolar and for SAM 16 $\mu$Molar. The pH maximum for the enzyme from this source is 7.6.Methyl chloride transferase activity was also detected in the halophytic plant, Batis maritima. The enzyme from this plant can be induced by salt stress and has been purified to homogeneity. We hope to clone the gene for this enzyme and further study its possible role in salt tolerance.U of I OnlyETDs are only available to UIUC Users without author permissio