Methyltetrahydromethanopterin as an intermediate in methanogenesis from acetate in Methanosarcina barkeri |
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Authors: | Reinhard Fischer Rudolf K. Thauer |
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Affiliation: | 1. Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universit?t, Karl-von-Frisch-Strasse, D-3550, Marburg, Germany
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Abstract: | Cell extracts (100,000×g) of acetate grown Methanosarcina barkeri (strain MS) catalyzed CH4 and CO2 formation from acetyl-CoA with specific activities of 50 nmol·min-1·mg protein-1. CH4 formation was found to be dependent on tetrahydromethanopterin (H4MPT) (apparent K M=4 μM), coenzyme M (H-S-CoM), and 7-mercaptoheptanoylthreonine phosphate (H-S-HTP=component B) rather than on methanofuran (MFR) and coenzyme F420 (F420). Methyl-H4MPT was identified as an intermediate. This compound accumulated when H-S-CoM and H-S-HTP were omitted from the assays. These and previous results indicate that methanogenesis from acetate proceeds via acetyl phosphate, acetyl-CoA, methyl-H4MPT, and CH3-S-CoM as intermediates. The disproportionation of formaldehyde to CO2 and CH4 was also studied. This reaction was shown to be dependent on H4MPT, MFR, F420, H-S-CoM, and H-S-HTP. |
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Keywords: | Methanogenesis from acetate Methanopterin Methanofuran Coenzyme F420 Coenzyme M 7-Mercaptoheptanoylthreonine phosphate (=component B) Methanosarcina barkeri |
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