Oxidase, superoxide dismutase, and hydrogen peroxide reductase activities of methanobactin from types I and II methanotrophs. J Inorg Biochem 2008 Aug;102(8):1571-80
Date
03/29/2008Pubmed ID
18372044DOI
10.1016/j.jinorgbio.2008.02.003Scopus ID
2-s2.0-46749119453 (requires institutional sign-in at Scopus site) 57 CitationsAbstract
Methanobactin (mb) is a copper-binding chromopeptide that appears to be involved in oxidation of methane by the membrane-associated or particulate methane monooxygenase (pMMO). To examine this potential physiological role, the redox and catalytic properties of mb from three different methanotrophs were examined in the absence and presence of O(2). Metal free mb from the type II methanotroph Methylosinus trichosporium OB3b, but not from the type I methanotrophs Methylococcus capsulatus Bath or Methylomicrobium album BG8, were reduced by a variety of reductants, including NADH and duroquinol, and catalyzed the reduction of O(2) to O(2)(-). Copper-containing mb (Cu-mb) from all three methanotrophs showed several interesting properties, including reductase dependent oxidase activity, dismutation of O(2)(-) to H(2)O(2), and the reductant dependent reduction of H(2)O(2) to H(2)O. The superoxide dismutase-like and hydrogen peroxide reductase activities of Cu-mb were 4 and 1 order(s) of magnitude higher, respectively, than the observed oxidase activity. The results demonstrate that Cu-mb from all three methanotrophs are redox-active molecules and oxygen radical scavengers, with the capacity to detoxify both superoxide and hydrogen peroxide without the formation of the hydroxyl radicals associated with Fenton reactions. As previously observed with Cu-mb from Ms. trichosporium OB3b, Cu-mb from both type I methanotrophs stimulated pMMO activity. However, in contrast to previous studies using mb from Ms. trichosporium OB3b, pMMO activity was not inhibited by mb from the two type I methanotrophs at low copper to mb ratios.
Author List
Choi DW, Semrau JD, Antholine WE, Hartsel SC, Anderson RC, Carey JN, Dreis AM, Kenseth EM, Renstrom JM, Scardino LL, Van Gorden GS, Volkert AA, Wingad AD, Yanzer PJ, McEllistrem MT, de la Mora AM, DiSpirito AAMESH terms used to index this publication - Major topics in bold
CatalysisFree Radical Scavengers
Hydrogen Peroxide
Imidazoles
Methylococcus capsulatus
Methylosinus trichosporium
Oligopeptides
Oxidation-Reduction
Oxidoreductases
Oxygenases
Peroxidases
Superoxide Dismutase
Superoxides