Krebs, Eggleston 1940 Biochem J
| Krebs HA, Eggleston LV (1940) The oxidation of pyruvate in pigeon breast muscle. Biochem J 34:442-59. https://doi.org/10.1042/bj0340442 |
Krebs HA, Eggleston LV (1940) Biochem J
Abstract: Pyruvate is very readily oxidized in animal tissues, yet little is known about the immediate products of its oxidation. Such oxidative reactions of pyruvate as are known to occur - dismutation, formation of succinate, acetate or ketone bodies - are side reactions whose significance varies from tissue to tissue: in no tissue can these reactions account for the total oxidation, and in some tissues, such as muscle or kidney, they account for even less than 20 %.
We have tried to elucidate the oxidation of pyruvate in pigeon breast muscle by studying in detail the factors governing the oxidation. We find that fumarate acts as catalyst in the oxidation of pyruvate and that malonate breaks the catalysis when one molecule of pyruvate has reacted with one molecule of fumarate.
• Bioblast editor: Gnaiger E
Selected quotes
- Minced pigeon breast muscle: 267 mg mw = 53 mg md; md/mw = 0.20
- 40 °C: The best medium for experiments on the utilization of pyruvate is calcium-free phosphate saline. .. Calcium when present in concentrations occurring in blood serum strongly inhibits the removal of pyruvate.
- The extra gas exchange caused by the addition of pyruvate is much too small to account for the removal of the pyruvate and we must therefore conclude that the added pyruvate competes for the 02 with the substrates normally present in the tissue and suppresses their oxidation. .. pyruvate is used as an inhibitor of the oxidation of citrate and alpha-ketoglutarate. - Comment: Incomplete or zero additivity.
- Szent-Gyögyi has shown that fumarate increases the 02 usage of muscle suspensions, especially in the presence of malonate. When the malonate concentration is low (0.001 M) .. fumarate acts like a catalyst and the extra 02 uptake may therefore amount to a multiple of the quantity required for its complete oxidation. .. when the concentration of malonate is high (0.0025 M) .. we find the additional 02 uptake caused by fumarate to be proportional to the quantity of fumarate added. - Comment: Excess additivity at low malonate, and complete additivity at high malonate concentration.
- .. a direct reduction of fumarate to succinate is inhibited by malonate (see Table 8, anaerobic experiment).
- Pyruvate .. is preferentially oxidized when several substrates are present; in other words it suppresses the oxidation of other substrates and an excess of pyruvate would therefore be expected to cause an accumulation of intermediates. The experiments show that this is the case if fumarate together with an excess of pyruvate is added. alpha-Ketoglutarate appeared in quantities reaching about 50 % of the maximum to be expected and citrate in quantities reaching about 15 %.
- Muscle suspensions: .. phosphate saline, made up by mixing 1000 mL 0.9 % NaCl, 40 mL 1-15 % KCI, 10 mL 3.84 % MgSO4, 7 H2O and 300 mL phosphate buffer, pH 7-4. The latter was prepared by dissolving 17-8 g Na2HPO4, 2 H20 and 20 mL N HCI in 1 L.
Labels: MiParea: Respiration
Organism: Birds
Tissue;cell: Skeletal muscle
Preparation: Homogenate
Enzyme: TCA cycle and matrix dehydrogenases
Pathway: N
Made history
