scholarly journals Nitroreductase activity of NADH dehydrogenase of the respiratory redox chain

1989 ◽  
Vol 257 (3) ◽  
pp. 859-863 ◽  
Author(s):  
G E Smyth ◽  
B A Orsi
Keyword(s):  
Cytochrome C ◽  
Complex I ◽  
Nadh Dehydrogenase ◽  
Liver Mitochondria ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Inner Membrane ◽  
Cytochrome C Reductase ◽  
Redox Chain ◽  
Nadh Cytochrome ◽  
Nitroreductase Activity

1. An NADH-dependent nitroreductase from the inner membrane of ox liver mitochondria copurified with Complex I of the respiratory redox chain (NADH:ubiquinone oxidoreductase, EC 1.6.5.3). 2. The corresponding nitroreductase from ox heart mitochondria co-purified with the NADH-cytochrome c reductase of Mahler, Sarkar & Vernon [(1952) J. Biol. Chem. 199, 585-597] [NADH: (acceptor) oxidoreductase, EC 1.6.99.3], a component of Complex I that contains the FMN. 3. The mitochondrial nitroreductase activity is attributed to the flavoprotein component of Complex I.

scholarly journals AN ELECTRON-TRANSPORT SYSTEM ASSOCIATED WITH THE OUTER MEMBRANE OF LIVER MITOCHONDRIA

1967 ◽  
Vol 32 (2) ◽  
pp. 415-438 ◽  
Author(s):  
Gian Luigi Sottocasa ◽  
Bo Kuylenstierna ◽  
Lars Ernster ◽  
Anders Bergstrand
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Outer Membrane ◽  
Respiratory Chain ◽  
Transport System ◽  
Cytochrome B5 ◽  
Liver Mitochondria ◽  
Electron Transport System ◽  
Cytochrome C Reductase ◽  
Nadh Cytochrome

Preparations of rat-liver mitochondria catalyze the oxidation of exogenous NADH by added cytochrome c or ferricyanide by a reaction that is insensitive to the respiratory chain inhibitors, antimycin A, amytal, and rotenone, and is not coupled to phosphorylation. Experiments with tritiated NADH are described which demonstrate that this "external" pathway of NADH oxidation resembles stereochemically the NADH-cytochrome c reductase system of liver microsomes, and differs from the respiratory chain-linked NADH dehydrogenase. Enzyme distributation data are presented which substantiate the conclusion that microsomal contamination cannot account for the rotenone-insensitive NADH-cytochrome c reductase activity observed with the mitochondria. A procedure is developed, based on swelling and shrinking of the mitochondria followed by sonication and density gradient centrifugation, which permits the separation of two particulate subfractions, one containing the bulk of the respiratory chain components, and the other the bulk of the rotenone-insensitive NADH-cytochrome c reductase system. Morphological evidence supports the conclusion that the former subfraction consists of mitochondria devoid of outer membrane, and that the latter represents derivatives of the outer membrane. The data indicate that the electron-transport system associated with the mitochondrial outer membrane involves catalytic components similar to, or identical with, the microsomal NADH-cytochrome b5 reductase and cytochrome b5.

scholarly journals ENZYMATIC PROPERTIES OF THE INNER AND OUTER MEMBRANES OF RAT LIVER MITOCHONDRIA

1968 ◽  
Vol 38 (1) ◽  
pp. 158-175 ◽  
Author(s):  
Carl Schnaitman ◽  
John W. Greenawalt
Keyword(s):  
Cytochrome C ◽  
Outer Membrane ◽  
Rat Liver ◽  
Soluble Fraction ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Membrane ◽  
Cytochrome C Reductase ◽  
Membrane Matrix ◽  
Matrix Fraction

Treatment of rat liver mitochondria with digitonin followed by differential centrifugation was used to resolve the intramitochondrial localization of both soluble and particulate enzymes. Rat liver mitochondria were separated into three fractions: inner membrane plus matrix, outer membrane, and a soluble fraction containing enzymes localized between the membranes plus some solublized outer membrane. Monoamine oxidase, kynurenine hydroxylase, and rotenone-insensitive NADH-cytochrome c reductase were found primarily in the outer membrane fraction. Succinate-cytochrome c reductase, succinate dehydrogenase, cytochrome oxidase, ß-hydroxybutyrate dehydrogenase, α-ketoglutarate dehydrogenase, lipoamide dehydrogenase, NAD- and NADH-isocitrate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase, and ornithine transcarbamoylase were found in the inner membrane-matrix fraction. Nucleoside diphosphokinase was found in both the outer membrane and soluble fractions; this suggests a dual localization. Adenylate kinase was found entirely in the soluble fraction and was released at a lower digitonin concentration than was the outer membrane; this suggests that this enzyme is localized between the two membranes. The inner membrane-matrix fraction was separated into inner membrane and matrix by treatment with the nonionic detergent Lubrol, and this separation was used as a basis for calculating the relative protein content of the mitochondrial components. The inner membrane-matrix fraction retained a high degree of morphological and biochemical integrity and exhibited a high respiratory rate and respiratory control when assayed in a sucrose-mannitol medium containing EDTA.

scholarly journals Changes in Microsomal Electron Transport of Plant Storage Tissues Induced by Slicing and Aging

1972 ◽  
Vol 25 (1) ◽  
pp. 103 ◽  
Author(s):  
JM Rungie ◽  
JT Wiskich
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Transport ◽  
Cytochrome C ◽  
Nadh Dehydrogenase ◽  
Microsomal Protein ◽  
Partial Recovery ◽  
Cytochrome C Reductase ◽  
Nadh Cytochrome ◽  
Induced Changes ◽  
Plant Storage

Slicing turnip, swede, and beet storage tissues induced 20-100% loss of micro-somal NADH dehydrogenase activities within 10 min. Subsequent washing of the slices resulted in partial recovery of some activities particularly NADH-cytochrome c reductase which reached a maximum after 24 hr aging then again declined. Slicing also induced a 20% decrease in microsomal protein but this loss was recovered after 5-10 hr aging. These induced changes correlated with reported changes in the ultra-structure of the endoplasmic reticulum.

scholarly journals The effect of rate limitation by cytochrome c on the redox state of the ubiquinone pool in reconstituted NADH: cytochrome c reductase

1987 ◽  
Vol 247 (3) ◽  
pp. 657-662 ◽  
Author(s):  
J S Reed ◽  
C I Ragan
Keyword(s):  
Steady State ◽  
Cytochrome C ◽  
Complex I ◽  
Redox State ◽  
Electron Flow ◽  
State Level ◽  
Steady State Level ◽  
Cytochrome C Reductase ◽  
Quinone Reduction ◽  
Nadh Cytochrome

The kinetic model of Ragan & Cottingham [(1985) Biochim. Biophys. Acta 811, 13-31] for electron transport through a mobile pool of quinone predicts that, under certain conditions, the normal linear dependence of electron flow on the degree of reduction (or oxidation) of the quinone should no longer be found. These conditions can be met by reconstituted NADH: cytochrome c reductase (Complex I-III from bovine heart) when electron flow is rate-limited by a low concentration of cytochrome c. We show that, in such a system, the dependence of activity (varied by inhibition with rotenone) on the steady-state level of quinone reduction is indeed non-linear and very closely accounted for by the theory.

scholarly journals Properties of a cytochrome c-enriched light particulate fraction isolated from the photosynthetic bacterium Rhodopseudomonas spheroides

1978 ◽  
Vol 174 (1) ◽  
pp. 267-275 ◽  
Author(s):  
J Barrett ◽  
C N Hunter ◽  
O T G Jones
Keyword(s):  
Cytochrome C ◽  
Sodium Dodecyl ◽  
Photosynthetic Bacterium ◽  
Particulate Fraction ◽  
Cytochrome C Reductase ◽  
Cytochrome C2 ◽  
Succinate Cytochrome C Reductase ◽  
Bulk Membrane ◽  
Nadh Cytochrome ◽  
Rhodopseudomonas Spheroides

Differential centrifugation of suspensions of French-press-disrupted Rhodopseudomonas spheroides yielded a light particulate fraction that was different in many properties from the bulk membrane fraction. It was enriched in cytochrome c and had a low cytochrome b content. When prepared from photosynthetically grown cells this fraction had a very low specific bacteriochlorophyll content. The cytochrome c of the light particles differed in absorption maxima at 77K from cytochrome c2 attached to membranes; there was pronounced splitting of the alpha-band, as is found in cytochrome c2 free in solution. Potentiometric titration at A552–A540 showed the presence of two components that fitted an n = 1 titration; one component had a midpoint redox potential of +345mV, like cytochrome c2 in solution, and the second had E0′ at pH 7.0 of +110 mV, and they were present in a ratio of approx. 2:3. Difference spectroscopy at 77K showed that the spectra of the two components were very similar. More of a CO-binding component was present in particles from photosynthetically grown cells. Light membranes purified by centrifugation on gradients of 5–60% (w/w) sucrose retained the two c cytochromes; they contained no detectable succinate-cytochrome c reductase or bacteriochlorophyll and very little ubiquinone, but they contained NADH-cytochrome c reductase and some phosphate. Electrophoresis on sodium dodecyl sulphate/polyacrylamide gels showed that the light membranes of aerobically and photosynthetically grown cells were very similar and differed greatly from other membrane fractions of R. spheroides.

Endoplasmic reticulum membrane isolated from small-intestinal epithelial cells: enzyme and protein components

1981 ◽  
Vol 52 (1) ◽  
pp. 215-222
Author(s):  
M. Fujita ◽  
H. Ohta ◽  
T. Uezato
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Cytochrome C ◽  
Endoplasmic Reticulum Membrane ◽  
Dependent Manner ◽  
Cytochrome C Reductase ◽  
Basolateral Membranes ◽  
Nadh Cytochrome ◽  
Protein Components ◽  
A Minor

Endoplasmic reticulum membrane-rich fraction was obtained by subfractionation of the light microsomes from mouse jejunal mucosal epithelial cells. It was marked by high glucose-6-phosphatase, NADPH-cytochrome c reductase, and NADH-cytochrome c reductase activities and low Na+,K+-ATPase activity. The enrichment of Na+,K+-ATPase was 180-fold higher in the basolateral membranes than in the endoplasmic reticulum membrane-rich fraction relative to glucose-6-phosphatase. The protein peak that was phosphorylated in a Na-dependent manner was prominent in the basolateral membranes while it was a minor peak in the endoplasmic reticulum membrane-rich fraction. Under the electron microscope the fraction was seen to be composed of homogeneous small vesicles with thin smooth membranes.

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