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oai:www.ideals.illinois.edu:2142/22839 2023-07-10 col_2142_5131 col_2142_16338 com_2142_5130 com_2142_16337 com_2142_14793 com_2142_8903

Wolfe, R.S. Bobik, Thomas Aquinas 2011-05-07T13:53:12Z 2011-05-07T13:53:12Z 10000-01-01 1990 The initial step of methanogenesis from CO$\sb2$ is the formation of formyl-methanofuran (formyl-MFR) from methanofuran, CO$\sb2$ and H$\sb2$. This reaction is not measurable in vitro unless activated. The enzymology, and the activation of this reaction were studied. It was found that the heterodisulfide of 2-mercaptoethanesulfonic acid and N-(7-mercaptoheptanoyl)threonine-O$\sp3$-phosphate (CoM-S-S-HTP) was directly involved in the activation of formyl-MFR formation. Preliminary evidence indicated that CoM-S-S-HTP activated electron transfer to formyl-MFR formation; CoM-S-S-HTP was found to activate an unknown electron carrier present in cell extracts of Methanobacterium, and the low potential reducing agent titanium-(III)$\cdot$citrate was found to bypass the CoM-S-S-HTP requirement of formyl-MFR synthesis. Additionally, CoM-S-S-HTP was shown to be a product of the methyl-reductase and the fumarate reductase reactions, and evidence indicated that each of these reactions activated formyl-MFR formation. Moreover, CoM-S-S-HTP was shown to be reduced by a heterodisulfide reductase and this reduction inactivated formyl-MFR formation. Fractionation procedures were employed to resolve cell extract into two components each of which was required for formyl-MFR formation. One fraction (in the presence of CoM-S-S-HTP) reduced the redox dye metronidazole with electrons from H$\sb2$, and the other fraction contained formyl-MFR dehydrogenase activity. Neither ATP nor a membrane fraction was required to reconstitute formyl-MFR formation, and the non-deazaflavin reducing hydrogenase was sufficient for formyl-MFR formation. It was proposed that the activation of formyl-MFR formation was used to coordinate the rate of CO$\sb2$ fixation with the rates of methanogenesis and cell carbon synthesis. Made available in DSpace on 2011-05-07T13:53:12Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9021651.pdf: 4519553 bytes, checksum: b9b9f5e44768996a3fb0ca1716ded5ad (MD5) Previous issue date: 1990 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:00:22Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:28:33-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9021651 (UMI)AAI9021651 http://hdl.handle.net/2142/22839 eng Copyright 1990 Bobik, Thomas Aquinas Biology, Microbiology Formylmethanofuran formation in Methanobacterium thermoautotrophicum text Microbiology Microbiology University of Illinois at Urbana-Champaign Dissertation Ph.D.