Monooxygenases methan monooxygenase

In one study, a coarse-grained sand aquifer was injected with methane and oxygen to stimulate the production of methane monooxygenase (MMO) enzyme which is capable of degrading TCE (18). TCE, added at 60—100 )-lg/L, was degraded by 20—30%. Injected concentrations of methane and oxygen were approximately 20 mg/L and 32 mg/L, respectively. 

Rubrerythrin (Rr) was first isolated in 1988 from cellular extracts of D. vulgaris Hildenborough (38), and later also found in D. desulfuri-cans (39). Rr is constituted by two identical subunits of 22 kDa and it was shown that each monomer contains one Rd-like center, Fe(RS)4, and a diiron-oxo center similar to the ones found in methane monooxygenase (MMO) (40, 41) or ribonucleotide reductase (RNR-R2) (42). After aerobic purification, the UV-visible spectrum shows maxima at 492, 365, and 280 nm, and shoulders at 570 and 350 nm. This spectrum is similar to the ones observed for Rd proteins. From a simple subtraction of a typical Rd UV-vis spectrum (normalized to 492 nm) it is possible to show that the remainder of the spectrum (maxima at 365 nm and a shoulder at 460 nm) strongly resembles the spectrum of met-hemerythrin, another diiron-oxo containing protein. 

Fox BG, Bomeman JG, Wackett LP, et al. 1990. Haloalkane oxidation by the soluble methane monooxygenase irom Methylosinus trichosporium OB3b Mechanistic and environmental implications. Biochemistry 29 6419-6427. 

Patel RN, CT Hou, AI Laskin, A Felix (1982) Microbial oxidation of hydrocarbons properties of a soluble monooxygenase from a facultative methane-utilizing organisms Methylobacterium sp. strain CRL-26. Appl Environ Microbiol 44 1130-1137. 

Lipscomb ID (1994) Biochemistry of the soluble methane monooxygenase. Annu Rev Microbiol 48 371-399. 

Nguyen H-HT, AK Shiemka, S J Jacobs, BJ Hales, ME Lidstrom, S 1 Chan (1994) The nature of the copper ions in the membranes containing the particulate methane monooxygenase from Methylococcus capsu-latus (Bath). J Biol Chem 269 14995-15005. 

Sontoh S, JD Semrau (1998) Methane and trichloroethylene degradation by Methylosinus trichosporium OB3b expressing particulate methane monooxygenase. Appl Environ Microbiol 64 1106-1114. 

Zahn JA, AA DiSpirito (1996) Membrane associated methane monooxygenase from Methylococcus capsula-tus (Bath). J Bacterial 178 1018-1029. 

Methane monooxygenase may exist in either soluble (sMMO) or particulate (pMMO) forms. These display different substrate ranges and different rates of transformation rates, and most methanotrophs express only the latter form of the enzyme (Hanson and Hanson 1996). The particulate form of methane monooxygenase contains copper, or both copper... 

Enzymes necessary for the metabolism of a substrate may be induced by growth on structurally unrelated compounds. In the examples used for illustration, monooxygenases play a cardinal role as a result of the versatility of methane monooxygenase, while monooxygenases that may be involved in toluene degradation are discussed in Chapter 3, Part 1 and Chapter 8, Part 1. 

Methane, butane, and chloroform. Cells of Methylosinus trichosporium grown with methane and of Pseudomonas butanovora md My cobacterium vaccae grown with butane were able to partially degrade chloroform (Hamamura et al. 1997). Again this may be the result of the induction of monooxygenase activity. 

FIGURE 7.1 Examples of the reactions catalyzed by methane monooxygenase. 

Fox BG, Wa Froland, JE Dege, JD Lipscomb (1989) Methane monooxygenase from Methylosinus trichospo-rium OB3b. Purification and properties of a three-component system with a high specific activity from a type II methanotroph. J Biol Chem 264 10023-10033. 

The cometabolism of halogenated methanes has been examined in Nitrosomonas europaea and may putatively be mediated by ammonia monooxygenase. 

Oldenhuis R, RLJM Vink, DB Janssen, B Witholt (1989) Degradation of chlorinated aliphatic hydrocarbons by Methylosinus trichosporium OB3b expressing soluble methane monooxygenase. Appl Environ... 

Jahng D, TK Wood (1994) Trichloroethylene and chloroform degradation by a recombinant pseudomonad expresssing soluble methane monooxygenase from Methylosinus trichosporium OB3b. Appl Environ Microbiol 60 2473-2482. 

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