Studies in the formation of single carbon compounds from glycine

Pitts, John D (1963) Studies in the formation of single carbon compounds from glycine. PhD thesis, University of Glasgow.

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Abstract

1. A review of glycine and glyoxylate metabolism is presented. 2. Growing Escherichia coli PA 15 incorporate glycine C-2 into the methyl group of DNA thymine, the C-2 and C-8 positions of the RNA and DNA purine rings and the C-3 position of protein serine. The pathway whereby glycine C-2 is converted to suitable C1-units at the oxidation levels of formaldchyde and formate, has been investigated. 3. Cell-free extracts convert glyoxylate and glutamate to glycine and 2-oxoglutarate by transamination. The reaction is not inhibited by DNA which completely inhibits non-enzymic transamination under the conditions used. 4. The data indicate that the reverse reaction, the conversion of glycine to glyoxylate in the presence of 2-oxoglutarate and EDTA, does not play a significant role in glycine catabolism by cell-free extracts. 5. The incorporation of 2-14C glycine into the thymine, serine and purines is unaffected by the addition of glyoxylate or aminoacetone to the medium, and the incorporation pattern is not changed when the cells are grown on glycollate instead of glucose. 6. Washed-cell suspensions convert glycine C-1 to carbon dioxide and glycine C-2 to formaldehyde (or a compound readily hydrolysed to formaldehyde) and carbon dioxide. 7. An enzyme system, partially purified from crude extracts, converts 1 mole of glycine to 1 mole of carbon dioxide (derived from C-1), 1 mole of ammonia and a C1-compound (derived, f C-2) which can be isolated as formaldehyde. H4PtG and PIP are necessary cofactors; the reaction is not dependent on metal ions which are chelated by EDTA. The. overall reaction represents the oxidation of glycin: NAD+ is the primary 1,ctron acceptor,. but catalytic amounts can bo regenerated in the system by oxygen or benzyl viologen. 8. Free glyoxylate.is net in equilibrium with any intermediate of the glycine-splitting reaction. 9. Cell-free extracts readily oxidize formate to carbon dioxide, but do not convert glyoxylate to formate in Significant amounts. 10. A scheme for the formation of 01-units from glycine is suggested, which involves the concerted-participation of PtG, PIP ,and HAD. The initial products of the reaction are carbon dioxide, ammonia, NADH and hydroxmethyl-H4PtG (or metylene-H4PtG). 11. The metabolic significance of the glycine-splitting reaction is discussed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: J N Davidson
Keywords: Physiology
Date of Award: 1963
Depositing User: Enlighten Team
Unique ID: glathesis:1963-73183
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56
URI: http://theses.gla.ac.uk/id/eprint/73183

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