This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: biogenesis of methylhalides (plants)
|Superclasses:||Biosynthesis → Other Biosynthesis|
In recent years the destruction of the ozone layer due to the action of halogen radicals and its negative effects on earth has occupied scientific and popular imagination. Methyl halides from biogenic emissions are the main transporters of halogen radicals from the atmosphere to stratosphere. Of the halides, methyl chloride is the most abundant and is released from specific fungi and plants and by the burning of biomass. methyl bromide, which was extensively used as a soil fumigant and is known to strongly deplete stratospheric ozone, has been prohibited in recent times, but is produced by some marine organisms. methyl iodide has lesser half life that methyl chloride and methyl bromide but is known to affect the formation of marine aerosol formation and cloud condensation nuclei [Coulter99].
The anthropogenic, marine and terrestrial biogenic sources of halides are known [Ohsawa01, Coulter99], but the mechanisms of biosynthesis are poorly understood. The enzymes involved are halide ion methyltransferase (HMT) and halide/thiol methyltransferase (HTMT). Several flowering plant families are involved in the formation of methyl halides [Wuosmaa90, Attieh95].
Attieh95: Attieh JM, Hanson AD, Saini HS (1995). "Purification and characterization of a novel methyltransferase responsible for biosynthesis of halomethanes and methanethiol in Brassica oleracea." J Biol Chem 270(16);9250-7. PMID: 7721844
Coulter99: Coulter C, Hamilton JT, McRoberts WC, Kulakov L, Larkin MJ, Harper DB (1999). "Halomethane:bisulfide/halide ion methyltransferase, an unusual corrinoid enzyme of environmental significance isolated from an aerobic methylotroph using chloromethane as the sole carbon source." Appl Environ Microbiol 65(10);4301-12. PMID: 10508052
Itoh09: Itoh N, Toda H, Matsuda M, Negishi T, Taniguchi T, Ohsawa N (2009). "Involvement of S-adenosylmethionine-dependent halide/thiol methyltransferase (HTMT) in methyl halide emissions from agricultural plants: isolation and characterization of an HTMT-coding gene from Raphanus sativus (daikon radish)." BMC Plant Biol 9;116. PMID: 19723322
Ohsawa01: Ohsawa N, Tsujita M, Morikawa S, Itoh N (2001). "Purification and characterization of a monohalomethane-producing enzyme S-adenosyl-L-methionine: halide ion methyltransferase from a marine microalga, Pavlova pinguis." Biosci Biotechnol Biochem 65(11);2397-404. PMID: 11791711
Saxena98: Saxena D, Aouad S, Attieh J, Saini HS (1998). "Biochemical characterization of chloromethane emission from the wood-rotting fungus phellinus pomaceus." Appl Environ Microbiol 64(8);2831-5. PMID: 9687437
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