. The chemical activities of bacteria. Bacteria. ADDENDUM While this edition was in the press, Ochoa and co-workers have published a series of papers [J. biol. Chem., 1950, 187, 849 et seq.) dealing with the fixation of carbon dioxide by animal and bacterial cells. They have shown that COg will combine with pyruvic acid in the presence of reduced coenzyme I (in bacteria) to form malic acid directly, the enzyme con- cerned being known at present as the "malic enzyme":— CO2 + CH3. CO. COOH + CoE. H2 = + CoE. In the schemes put forward on pp. 135 and 137, the first st
. The chemical activities of bacteria. Bacteria. ADDENDUM While this edition was in the press, Ochoa and co-workers have published a series of papers [J. biol. Chem., 1950, 187, 849 et seq.) dealing with the fixation of carbon dioxide by animal and bacterial cells. They have shown that COg will combine with pyruvic acid in the presence of reduced coenzyme I (in bacteria) to form malic acid directly, the enzyme con- cerned being known at present as the "malic enzyme":— CO2 + CH3. CO. COOH + CoE. H2 = + CoE. In the schemes put forward on pp. 135 and 137, the first stage in CO2 fixation is shown as a carboxylation of pyruvic acid by reversal of oxalacetic decarboxylase. It has not been possible to demonstrate convincingly that the bacterial oxalacetic decarboxylase is reversible and the first stage in the fixation process should be represented as a direct formation of malic acid by the "mafic enzyme" without the intermediate forma- tion of oxalacetic acid. In the "citric acid cycle" outlined in Fig. 12, citric acid is shown as a side-product not involved in the reactions of the actual cycle. Evidence has accumulated during the past year that citric acid itself is involved in the cycle. It is formed by the condensation of acetyl-phosphate and oxalacetic acid and then gives rise to m-aconitic acid and the other substrates shown in the cycle. It is probable, in the light of the findings concerning the "malic enzyme," that the oxalacetic acid is formed via malic acid and not directly from CO2 and pyruvic acid as shown in Fig. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gale, E. F. (Ernest Frederick). New York, Academic Press
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectbacteria
