Three discrete coupling proteins in oxidative phosphorylation

Smith, Archie L.; Hansen, Marc

doi:10.1016/0006-291x(62)90251-6

Cited by 31 publications

(1 citation statement)

References 3 publications

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“…Because amytal is a specific inhibitor of NADH cytochrome c reductase (Smith and Hansen, 1962), electrons in the oxidation of L-proline do not flow through NAD enzymes to the cytochrome systems. This is in agreement with the report of Johnson and Strecker (1962) for the rat liver mitochondrial enzyme.…”

Section: Resultsmentioning

confidence: 99%

PROLINE OXIDASES IN HANSENULA SUBPELLICULOSA

Ling

Hedrick

1964

J Bacteriol

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Hansenula subpelliculosa can use L-proline as a carbon and a nitrogen source after a 6to 8-hr induction period. However, they cannot use L-glutamate as both nitrogen and carbon sources unless the induction period is of several days' duration. Two L-proline oxidases were demonstrated in the mitochondrial preparation of this yeast. One forms the product A'-pyrroline-2-carboxylic acid (P2C), which is in equilibrium with a-keto-8-amino-valeric acid; the other forms the product A'-pyrroline-5-carboxylic acid (P5C), which is in equilibrium with glutamic-ysemialdehyde. The first-mentioned enzyme is induced when L-proline is the carbon source; the second appears to be constitutive, and is probably associated with the use of L-proline as a nitrogen source. The P2C-forming enzyme is specific for the i. isomer of proline, and is inactive against Lhydroxyproline. The enzyme activity is at its peak when the mitochondria are prepared from logarithmically grown cells, and is rapidly reduced after cells reach the stationary phase of growth. Kinetic studies with varying concentrations of substrate indicate a Michaelis-Menten constant of 2.45 X 10-2 M. Paper chromatographic studies, chemical tests with H202 , sensitivity to freezing, and spectral measurements indicate that proline oxidase from H. subpelliculosa mitochondria forms a product from L-proline which is like, if not identical to, P2C formed by the action of sheep kidney D-proline oxidase upon DL-proline. The soluble portion of the cell extract contains NAD+ enzymes which use either P2C (a-keto-6-amino-valeric acid) or P5C (glutamic-y-semialdehyde) as substrates. No glutamic dehydrogenase activity could be detected when L-glutamic acid and the nicotinamide adenine dinucleotide (NAD+) cofactor were added to the supernatant solution with the yeast enzymes. The presence of a dehydrogenase NAD+ enzyme for activity with P2C (a-keto-6-aminovaleric acid) has not been previously reported. liver. Working with mammalian liver and kidney, Blanchard et al. (1944) reported that L-proline was oxidized to A'-pyrroline-2-earboxylic acid

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Section: Resultsmentioning

confidence: 99%

PROLINE OXIDASES IN HANSENULA SUBPELLICULOSA

Ling

Hedrick

1964

J Bacteriol

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Oxidative Phosphorylierung in Mitochondrien

Schatz¹

1967

Angewandte Chemie

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Mitochondrien können aus ADP und anorganischem Phosphat ATP bilden, wobei der Energiebedarf durch die Atmung gedeckt wird. Dieser gekoppelte Prozeß wird als oxidative Phosphorylierung bezeichnet. In ausreichend mit Sauerstoff versorgten normalen tierischen Zellen wird auf diese Weise die Hauptmenge an ATP synthetisiert. Der Mechanismus der oxidativen Phosphorylierung ist unbekannt. Der Ablauf der Gesamtreaktion ist eng an die innere Mitochondrienmembran gebunden. Als erstes läßt sich ein energiereiches Primärprodukt nachweisen, das in noch unbekannter Weise ATP bildet. An der Kopplung von Atmung und ATP‐Synthese sind Proteine der inneren Mitochondrienmembran beteiligt, die als „Kopplungsfaktoren”︁ bezeichnet werden. Der Verlauf der oxidativen Phosphorylierung wird zur Zeit an drei Hypothesen diskutiert: der „chemischen”︁, der „chemiosmotischen”︁ und der „Konformationshypothese”︁. Eine Entscheidung zwischen diesen Hypothesen ist noch nicht möglich.

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Mitochondrial Oxidative Phosphorylation

Schatz

1967

Angew. Chem. Int. Ed. Engl.

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celeration of the release of the aldehyde (hydroxy-TPP).This observation should be of general importance t o catalysis processes involving covalently bonded intermediates. If the original substrate-catalyst bond is strengthened in the course of any reaction on the catalyst or enzyme, a co-catalyst that promotes the cleavage of the reaction product will strongly influence the stationary rate.3 . An extreme position among the aldehydes is occupied by the almost completely hydrated formaldehyde, whose K d value is lower by about three powers of ten. On the basis of our analogy, therefore, the stability of the bonding of active formaldehyde in the enzyme should be about three powers of ten greater than in the case of active acetaldehyde. This is the reason for the failure of the release of aldehyde to take place when glyoxylic acid is used as the substrate.

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Three discrete coupling proteins in oxidative phosphorylation

Cited by 31 publications

References 3 publications

PROLINE OXIDASES IN HANSENULA SUBPELLICULOSA

PROLINE OXIDASES IN HANSENULA SUBPELLICULOSA

Oxidative Phosphorylierung in Mitochondrien

Mitochondrial Oxidative Phosphorylation

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