1932

Abstract

Most methanogenic archaea reduce CO with H to CH. For the activation of H, they use different [NiFe]-hydrogenases, namely energy-converting [NiFe]-hydrogenases, heterodisulfide reductase-associated [NiFe]-hydrogenase or methanophenazine-reducing [NiFe]-hydrogenase, and F-reducing [NiFe]-hydrogenase. The energy-converting [NiFe]-hydrogenases are phylogenetically related to complex I of the respiratory chain. Under conditions of nickel limitation, some methanogens synthesize a nickel-independent [Fe]-hydrogenase (instead of F-reducing [NiFe]-hydrogenase) and by that reduce their nickel requirement. The [Fe]-hydrogenase harbors a unique iron-guanylylpyridinol cofactor (FeGP cofactor), in which a low-spin iron is ligated by two CO, one C(O)CH-, one S-CH-, and a sp2-hybridized pyridinol nitrogen. Ligation of the iron is thus similar to that of the low-spin iron in the binuclear active-site metal center of [NiFe]- and [FeFe]-hydrogenases. Putative genes for the synthesis of the FeGP cofactor have been identified. The formation of methane from 4 H and CO catalyzed by methanogenic archaea is being discussed as an efficient means to store H.

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/content/journals/10.1146/annurev.biochem.030508.152103
2010-07-07
2024-10-16
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/content/journals/10.1146/annurev.biochem.030508.152103
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  • Article Type: Review Article
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