Biosynthesis of the 1,3,4,6-hexanetetracarboxylic acid subunit of methanofuran
/sup 2/H- and /sup 13/C-labeled precursors were used to establish the pathway for the biosynthesis of the 1,3,4,6-hexanetetracarboxylic acid (TCA) component of methanofuran, which is found in some methanogenic bacteria. The extent and position of incorporation of label into TCA were measured from the mass spectrum of the tetramethyl ester of TCA that was prepared from methanofuran present in cells grown in the presence of labeled acetate. (2,2,2-/sup 2/H/sub 3/)Acetate was found to incorporate deuterium into two separate sites of the TCA molecule, with one on each side of the symmetrical molecule. One site was found to be labeled 37% with deuterium, the same as for the glutamic acid present in the cells; the other site was labeled 77% with deuterium, the same as for the malonate-derived compounds in the cells. An analog of TCA, 1-hydroxy-1,3,4,6-hexanetetracarboxylic acid, found in methanofuran isolated from Methanobrevibacter smithii, was found to incorporate /sup 13/C/sub 2/ units from (1,2-/sup 13/C/sub 2/)acetate into three positions of the molecule. One of the acetate /sup 13/C/sub 2/ units was incorporated into the non-hydroxyl-containing side of the molecule (carbons 4, 5, and 6 and the C-6 carboxylic acid group), and two acetate units were incorporated into the hydroxyl-containing side of the molecule (carbons 1, 2, and 3 and the C-1 carboxylic acid group). On the basis of this and additional information, it is concluded that TCA is biosynthesized by the condensation of ..cap alpha..-ketoglutaric acid with malonic acid to form 1,1,2,4-butanetetracarboxylic acid, which is further condensed with a second molecule of malonate, in a series of reactions analogous to those observed during fatty acid biosynthesis, to form TCA.
- Research Organization:
- Virginia Polytechnic Institute and State Univ., Blacksburg
- OSTI ID:
- 6024894
- Journal Information:
- Biochemistry; (United States), Vol. 26:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBOXYLIC ACIDS
BIOCHEMISTRY
BIOSYNTHESIS
LABELLED COMPOUNDS
ACETATES
CARBON 13
DEUTERIUM COMPOUNDS
FURANS
GAS CHROMATOGRAPHY
MASS SPECTROSCOPY
METHANOGENIC BACTERIA
BACTERIA
CARBON ISOTOPES
CARBOXYLIC ACID SALTS
CHEMISTRY
CHROMATOGRAPHY
EVEN-ODD NUCLEI
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
SEPARATION PROCESSES
SPECTROSCOPY
STABLE ISOTOPES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques