The pathway of oxidation of acetate in baker's yeast

Krebs, H. A.; Gurin, Samuel; Eggleston, L. V.

doi:10.1042/bj0510614

Cited by 137 publications

(52 citation statements)

References 20 publications

(7 reference statements)

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“…These results confirm that whilst in this organism the cycle largely serves to supply intermediates for organic syntheses (Krebs, Gurin & Eggleston, 1952), it nevertheless also plays an important part in the terminal oxidation mechanisms and the production of respiratory carbon dioxide. Lewis & Weinhouse (1951) found with Aspergillus niger that the distribution of isotopic activity in citric acid from cells metabolizing carboxyl-labelled acetate was consistent with the cycle being a major pathway for acetate utilization and citrate formation.…”

Section: Comparison With Other Organismssupporting

confidence: 76%

The Metabolic Significance of the Citric Acid Cycle in the Growth of the Fungus Zygorrhynchus moelleri

Moses

1957

Journal of General Microbiology

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SUMMARY: Cultures of the fungus Zygorrhynchus moelleri were grown in a glucoseacetate + ammonia + saltsmedium in the presence of either radioactive carbon dioxide, or acetate labelled in either the methyl-or the carboxyl-positions. After growth the protein was hydrolysed and the pattern of incorporation of radiocarbon into the amino acids was determined by chromatography and radioautography ; activity from carbon dioxide appeared in glutamic and aspartic acids, methionine, threonine, isoleucine, proline and arginine. With labelled acetate lysine and leucine were also radioactive. A pool of free amino acids was present in this fungus.Several amino acids were isolated from the three samples of hydrolysed proteirh and their specific activities were determined. Assuming that the tricarboxylic acid cycle operated in this organism, a number of predictions concerning the distribution of radiocarbon in certain amino acids which could be made were largely confirmed by the experimental findings. By partial degradation of glutamic and aspartic acids, followed by assay of the radioactivity in the products, it was possible to calculate that about 60% of the oxalacetate used for citrate synthesis was recycled C,-dicarboxylic acid ; 40 yo was synthesized from pyruvate and carbon dioxide. Approximately 25 yo of the total respiratory carbon dioxide evolved could be accounted for in terms of decarboxylations occurring within the citric acid cycle.

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Section: Comparison With Other Organismssupporting

confidence: 76%

The Metabolic Significance of the Citric Acid Cycle in the Growth of the Fungus Zygorrhynchus moelleri

Moses

1957

Journal of General Microbiology

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“…Aerobes when growing on fatty acids use, as an anaplerotic reaction, the glyoxylate bypass [148,149] (Fig. 9).…”

Section: A Novel Anaplerotic Sequence F O R the Citric-acid Cyclementioning

confidence: 99%

Citric‐acid cycle, 50 years on

Thauer

1988

European Journal of Biochemistry

157

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Many anaerobic bacteria can completely oxidize organic matter to C 0 2 with either sulfur, sulfate, or protons as electron acceptor. The sulfur-reducing bacteria and one genus of sulfate reducers use a modified citric-acid cycle with a novel anaplerotic sequence as pathway of terminal respiration. All other anaerobes use an alternative pathway, in which carbon monoxide dehydrogenase is a key enzyme and in which acetyl-CoA is cleaved into two C1 units at the oxidation level of CH30H and CO. Thus almost 50 years after the discovery of the citric acid cycle by Hans Krebs in 1937, a second pathway for acetyl-CoA oxidation was found.1987 marked the 50th anniversary of the discovery of the citric acid cycle. In 1937 Hans Krebs summarized the evidence for a cyclic sequence of reactions that explained the complete oxidation, by pigeon breast muscle, of an unidentified 'triose' derived from glycolysis. The paper was entitled " [11][12][13][14], and intracellular organization [15, 161. The book contains excellent up-to-date treatises of these topics which therefore will not be dealt within the following review.Until recently it was believed that the citric acid cycle operates only in aerobic organisms in a few denitrifiers (reduce NO, to N,) [20, 211, and in some phototrophic purple non-sulfur bacteria [22, 231. Under anaerobic conditions all other known chemotrophic organisms, in pure culture, were incapable of complete oxidation of organic matter. And there was also a theory to explain this observation: the oxidation of succinate to fumarate in the citric-acid cycle requires a terminal electron acceptor with a redox potential (E"') more positive than that of the fumarate/ succinate couple (+32 mV). Only O2 ( 0 2 / H 2 0 : E" = f 8 1 8 mV), NO; (NO;/NO;: E"' = +433 mV) and NO; (NO;/N2: E"' = +970 mV), rather than the electron acceptors used by anaerobes, appeared to meet these conditions The above consideration ignored that there was, in the literature, evidence for a mineralization of organic matter in anaerobic biotopes. Hoppe-Seyler, already in 1886, described the complete oxidation of cellulose in anaerobic sediments supplemented with CaSO,. The reducing equivalents were quantitatively recovered as H2S [25]. Later Jerrgensen Martens and Berner [30], and Winfrey and Zeikus [31] reported that in marine sediments carbohydrates, proteins, and fatty acids were mineralized in the absence of O2 and that sulfate, elemental sulfur, and thiosulfate [29] were the major electron acceptors used. Sterilized sediments did not mediate the conversion. It was, therefore, evident that an anaerobic pathway of terminal respiration must exist.Pfennig and collaborators were then the first to isolate one of these organisms. In 1976 Pfennig and Biebl [32] described ~4 1 .

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“…The component reactions of the citric acid cycle have also been shown to occur in many micro-organisms 32 and in plants. In some materials the rates of the individual steps are sufficiently rapid to justify the assumption, supported by isotope data, that the cycle represents the main terminal pathway of oxidation.…”

Section: Early Workmentioning

confidence: 99%

“…In yeasts, for example, the activities of the enzymes that oxidize the malate and citrate are at most 5-25% of the expected order. Moreover when 14 Clabelled acetate is oxidized by baker's yeast the intracellular dicarboxylic acids remain unlabelled, an observation which argues against the participation of the dicarboxylic acids in the oxidation of acetate 32 . It is true that these results may not be looked upon as conclusive because permeability barriers might prevent the mixing of substances arising as intermediates with those that are present in other compartments of the cell, and at present it is best to regard the terminal pathway of oxidation in yeast, and certain other microorganisms, e.g.…”

Section: Early Workmentioning

confidence: 99%

The Tricarboxylic acid cycle (revision number 25)

Ward¹

2015

Diapedia

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The pathway of oxidation of acetate in baker's yeast

Cited by 137 publications

References 20 publications

The Metabolic Significance of the Citric Acid Cycle in the Growth of the Fungus Zygorrhynchus moelleri

The Metabolic Significance of the Citric Acid Cycle in the Growth of the Fungus Zygorrhynchus moelleri

Citric‐acid cycle, 50 years on

The Tricarboxylic acid cycle (revision number 25)

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