On a possible mechanism of the adenosinetriphosphatase of liver mitochondria

Siekevitz, Philip; Löw, H.; Ernster, Lars; Lindberg, Olle R.

doi:10.1016/0006-3002(58)90197-5

Cited by 138 publications

(22 citation statements)

References 48 publications

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“…The DOC effects upon mitochondrial and microsomal reductases and diaphorases are comparable, and the DOC inactivation of mitochondrial (NADH-cytochrome c reductase can be reversed by dilution as in the case of the mierosomes. 4 The Mg++-dependent ATPase activity is in both cases tightly bound to a membranous component (60), and the cytochrome b5 extracted from mitochondria is similar to that of microsomal origin (61). A possible explanation of this parallelism is an extensive contamination of each of these two fractions by whole units or subunits that properly belong to the other.…”

Section: Discussionmentioning

confidence: 99%

Enzyme-Structure Relationships in the Endoplasmic Reticulum of Rat Liver

Ernster¹,

Siekevitz²,

Palade³

1962

The Journal of Cell Biology

718

153

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Subfractionation of preparations of rat liver microsomes with a suitable concentration of sodium deoxycholate has resulted in the isolation of a membrane fraction consisting of smooth surfaced vesicles virtually free of ribonucleoprotein particles. The membrane fraction is rich in phospholipids, and contains the microsomal NADH-cytochrome c reductase, NADH diaphorase, glucose-6-phosphatase, and ATPase in a concentrated form. The NADPH-cytochrome c reductase, a NADPH (or pyridine nucleotide unspecific) diaphorase, and cytochrome b5 are recovered in the clear supernatant fraction. The ribonucleoprotein particles are devoid of, or relatively poor in, the enzyme activities mentioned. Those enzymes which are bound to the membranes vary in activity according to the structural state of the microsomes, whereas those which appear in the soluble fraction are stable. From these findings the conclusion is reached that certain enzymes of the endoplasmic reticulum are tightly bound to the membranes, whereas others either are loosely bound or are present in a soluble form within the lumina of the system. Some implications of these results as to the enzymic organization of the endoplasmic reticulum are discussed.

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Section: Discussionmentioning

confidence: 99%

Enzyme-Structure Relationships in the Endoplasmic Reticulum of Rat Liver

Ernster¹,

Siekevitz²,

Palade³

1962

The Journal of Cell Biology

718

153

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“…Higher concentrations of antimycin A, however, caused a slight inhibition, which is attributed to a n increased H+ permeability induced by antimycin (cf. the stimulation of the ATPasc activity [18]). …”

Section: Methodsmentioning

confidence: 99%

The Mechanism of Ion Translocation in Mitochondria. 4. Coupling of K+ Efflux with Ca2+ Uptake

1970

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The translocation of Ca2+ across the mitochondria1 membrane in the absence of metabolism has been studied. The experimental system consists in coupling the downhill efflux of K+ from rotenone-valinomycin treated mitochondria to the uphill influx of Ca2+.The Vmax of the H+ driven Ca2+ uptake is 4 pg ionsxg protein-l~sec-l. The rate of Ca2+ uptake has the following properties: it is insensitive to oligomycin, cyanide or antimycin A; it is dependent on the concentration of Ca2+ and valinomycin, it is dependent on the external K+ and abolished above 13 mM K O ; it shows a saturation kinetics.The K+ driven Ca2+ uptake is inhibited by several agents, among which La3+, H+, dinitro- A model for the translocation of Ca2+ across the membrane is discussed which assumes that the fluxes of K+ and Ca2+ are coupled together through the operation of a common chemical translocator. The operation of the carrier is suggested also to be responsible for the metabolism linked uptake of Ca2+.Uphill translocation of Ca2+ has been observed in liver mitochondria in two instances :metabolism METHODSRat liver mitochondria prepared in 0.25M sucrose, 5 mM Tris-C1 a t pH 7.5, 0.5 mM EGTA were used throughout except in the final suspension of mitochondria when EGTA was omitted.Phospholipid depleted mitochondria were prepared according to the method of Fleischer et al. [15] using a mixture of water-acetone (90: 10, v/v), and

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“…of DL-thyroxine (obtained ATP-Dephosphorylation Freshly-prepared intact mitochondria of rat liver contain a so-called latent adenosine triphosphatase. ATPase activity can be manifested in these particles either by 2: 4-dinitrophenol (DNP-activated ATPase) or by physical and chemical agents which cause damage to the integrated structure of the mitochondria (Mg2+-activated ATPase) (Kielley and Kielley, 1951;Potter, Siekevitz and Simonson, 1953;Siekevitz, L6w, Ernster and Lindberg, 1958). The DNPactivated ATPase is generally considered (Hunter, 1956) to represent a reversal and diversion of the reactions which are responsible for the synthesis of ATP during the process of oxidative phosphorylation, whereas the Mg2+-activated ATPase probably represents some mal-function resulting from a disorganization of the otherwise integrated enzymic machinery of the latter process.…”

Section: Methodsmentioning

confidence: 99%

“…It has been shown that progressive ageing of isolated liver mitochondria leads to a labilization of the integrated functions as shown by the loss of DPN, a gradual decrease in the efficiency of oxidative phosphorylation and an increase in free (Mg2+-activated) ATPase. Concomitantly, the DNP-activated ATPase decreases so that eventually a situation may be reached in which DNP no longer activates the ATPase in the presence of Mg2+ (Potter et al, 1953;Siekevitz et al, 1958). Hence the presence of free ATPase activity and the level of the DNP-activated ATPase relative to the former activity, may provide some information about the degree of intactness of the biochemical features of isolated mitochondria.…”

Section: Methodsmentioning

confidence: 99%

Studies on Isolated Tumour Mitochondria: Biochemical Properties of Mitochondria from Hepatomas with Special Reference to a Transplanted Rat Hepatoma of the Solid Type

Emmelot¹,

Bos²,

Brombacher³

et al. 1959

Br J Cancer

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A BASIC policy in the study of neoplastic growth is to compare the metabolic characteristics of a tumour with those of the homologous normal tissue. In the long run this may lead to a better understanding of the neoplastic diseases and furnish some rational clue(s) for a chemotherapy of cancer.The rat liver is a suitable tissue for study because of its relatively uniform composition, the ease of obtaining a sufficient quantity of tissue and the possibility of inducing experimental hepatomas with chemical agents. In the experiments to be reported in the present paper, mitochondria were isolated from a transplanted rat hepatoma and studied in respect to a number of important enzymic reactions. The original tumour (case No. BY 252) arose several years ago in a rat of our inbred colony as a result of feeding DAB*. The following favourable circumstances allow that a strict comparison can be made between the enzymic activities of the hepatoma and normal liver mitochondria. The intraperitoneally transplanted BY 252 rat hepatoma is composed of a uniform population of undifferentiated liver tumour cells classified as a carcinoma solidum. Since fibrous elements are virtually absent, the tumour shows the same softness as normal rat liver and homogenization of the two types of tissue can thus be performed in exactly the same way.The levels of the free and DNP-activated ATPases, oxidative phosphorylation in the absence and presence of thyroxine and fatty acid oxidation of the hepatoma particles have been studied. The results of these experiments clearly showed that the hepatoma mitochondria were more labile in vitro than normal rat liver mitochondria.Another transplanted rat hepatoma which has become a favourite test object in recent years is the Novikoff hepatoma (Novikoff, 1957). The latter tumour and the BY 252 hepatoma show approximately the same rate of growth and a similar histological structure; both have been induced by DAB. According to the Greenstein concept, undifferentiated tumours, as a class, tend to resemble each other metabolically more than they do their tissue of origin (Greenstein, 1953(Greenstein, , 1956). The pertinent data on which this concept is based, apply not only to metabolic functions performed by organo-typical enzyme systems-such as those mediating the formation of urea in the liver-but also to enzymes which are * Abbreviations are used as follows: DAB =p-dimethylaminoazobenzene, AAT = o-aminoazotoluene, ATP -= adenosine triphosphate, DNP -= 2,4: dinitrophenol, DPN = diphosphopyridine nucleotide, NAA = nicotinamide, EDTA = ethylenediamine tetra-acetate, a-OC = a-oxycaproato.

show abstract

On a possible mechanism of the adenosinetriphosphatase of liver mitochondria

Cited by 138 publications

References 48 publications

Enzyme-Structure Relationships in the Endoplasmic Reticulum of Rat Liver

Enzyme-Structure Relationships in the Endoplasmic Reticulum of Rat Liver

The Mechanism of Ion Translocation in Mitochondria. 4. Coupling of K+ Efflux with Ca2+ Uptake

Studies on Isolated Tumour Mitochondria: Biochemical Properties of Mitochondria from Hepatomas with Special Reference to a Transplanted Rat Hepatoma of the Solid Type

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