Oxidation of fatty acids by cell-free extracts of a vibrio

Abstract

Cell-free extracts of Clo8tridium kluyveri catalyse the oxidation by molecular oxygen of certain fatty acids with four to eight carbon atoms (Stadtman & Barker, 1949a, b). Work with this obligate anaerobe has shed much light on mechanisms by which fatty acids are oxidized biologically (for reviews see Barker, 1951;Stadtman & Stadtman, 1953), but little progress has been made with aerobic microorganisms since hitherto it has not been possible to prepare from them extracts with biochemical activities comparable with those from C. kluyveri. Indeed, studies of enzyme induction in whole cells of Serratia marceacen8 gave results apparently opposed to ,B-oxidation of saturated fatty acids with 2 to 14 carbon atoms (Silliker & Rittenberg, 1951. It has been suggested (Stadtman & Stadtman, 1953), however, that in these experiments the enzymes induced may be those responsible for activation of the free fatty acids and not for their oxidation; and Ivler, Wolfe & Rittenberg (1955) have prepared an extract from P8eudomona8 fluore8cen8 which produced acetate from n-decanoate with the consumption of only 1 tmole of oxygen/umole of substrate, and which further suggested ,8-oxidation by its cofactor requirements and in the formation of a hydroxamate of n-decanoate. The evidence of Webley, Duff & Farmer (1955) strongly supported fioxidation as the mechanism of breakdown of wphenyl-substituted fatty acids by whole cells of Nocardia opaca. Various investigations (Dagley & Rodgers, 1953;Dagley & Johnson, 1956; Dagley & Walker, 1956) indicate that the tricarboxylic acid cycle operates for the vibrio used in the present work, and Krebs, Gurin & Eggleston (1952) have suggested that for micro-organisms generally the main function of the cycle is to provide intermediates for use in synthesis. When the carbon * Part 75: El Masri, Smith & Williams (1958).

A direct pathway for the metabolism of propionate in cell extracts from Moraxella Iwoffi

“…Although it might be expected that the initial reactions concerned with the oxidation of both propionate and acetate would involve the formation of CoA derivatives, the addition of CoA, ATP or NAD+ singly or together had no effect on the rates of oxidation observed with these extracts. A similar situation had previously been found with this organism when extracts from octanoate-grown cells were tested for their ability to oxidize octanoate (Callely, Dagley & Hodgson, 1958). In this case a requirement for these cofactors was established by treatment of the extract with Dowex 2.…”

β-Oxidation of fatty acids by Leptospira

“…The results of these studies demonstrate that leptospires have the enzymes necessary to use P-oxidation for fatty acid degradation, as do other bacteria (4,8,12,20). Production of acetate and C 0 2 from fatty acid oxidation, demonstrated in separate studies to be published from this laboratory, provides additional support for this hypothesis.…”

The metabolism of C2 compounds in micro-organisms. 4. Synthesis of cell materials from acetate by Aspergillus niger

“…and those of succinate-grown cells less than 0-02. This indicates that in A. niger, as in other micro-organisms (Smith & Gunsalus, 1955Olson, 1959;Callely, Dagley & Hodgson, 1958;Kornberg, Gotto & Lund, 1958;Kornberg & Lund, 1959;Kornberg et al 1960a;Kornberg, Phizackerley & Sadler, 1960 b) isocitratase is formed only under conditions Vol. 77 necessitating the net formation of cellular materials from acetate, and thus supports the postulated role of the glyoxylate cycle in the growth of the organism on acetate.…”