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|Title:||The Structure of The Carbon Dioxide Reduction Factor, a Novel Carbon Carrier in Methanobacterium Thermoautotrophicum|
|Author(s):||Leigh, John Arthur|
|Department / Program:||Microbiology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Carbon dioxide reduction factor (CDR factor) was originally detected in a low-molecular-weight fraction of cell extract from Methanobacterium thermoautotrophicum that was required for methane production from CO(,2) by resolved cell extracts. The CDR factor of Romesser and Wolfe (Romesser, J. A., and Wolfe, R. S. (1982) Zbl. Bakt. Hyg., I. Abt. Orig. C 3:271-276) was separated into two components both of which were highly purified. One component was methanopterin (Keltjens, J. T., and Vogels, G. D. (1981) in Microbial Growth on C(,1) Compounds (Dalton, H., ed) pp. 152-158, Heydon and Son, Ltd., London), and for the other component the name CDR factor was retained. No known coenzymes tested substituted in the methane-producing assays for CDR factor and methanopterin, both of which were stable to boiling and exposure to air. The addition of CDR factor (0.8 (mu)g) and methanopterin (50 (mu)g) to the assay mixture increased by 12-fold the amount of methane formed from CO(,2).
The structure of CDR factor was determined, using nuclear magnetic resonance, mass, and ultraviolet spectrometry. CDR factor can be described as 4-(4,5-dicarboxyoctanoyl-(gamma)-L-glutamyl-(gamma)-L-glutamyl-p(2-aminoethyl)anisolyl)-furfuryl amine.
In a reaction mixture under an atmosphere of hydrogen and ('14)CO(,2), in the absence of methanopterin, CDR factor became labelled. Proton NMR spectrometry revealed that a formyl group was bound to the primary amine of CDR factor. (('14)C) formyl-CDR factor was enzymically converted to (('14)C) methane in the presence of CH(,3)-S-CoM and methanopterin. In the absence of methanopterin, a substantial portion of the label was converted to ('14)CO(,2). When CH(,3)-S-CoM was replaced by HS-CoM, almost all of the label was converted to ('14)CO(,2), indicating that the CH(,3)-S-CoM stimulation phenomenon (RPG effect) functions at the formyl level of oxidation as well as in the initial binding of CO(,2).
Methanopterin was shown to contain a para-substituted phenyl group, a glutamate moiety, two methyl groups, and some carbohydrate. The most likely molecular formula was C(,30)H(,41)N(,6)O(,16)P.
Conventional water-soluble vitamins were found to be present in methanogens at generally lower levels than in other bacteria tested.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2014-12-16|