scholarly journals Reduction of Cytochrome Oxidase by Reduced Diphosphopyridine Nucleotide-Cytochrome c Reductase

1959 ◽  
Vol 234 (2) ◽  
pp. 392-397
Author(s):  
S.J. Cooperstein ◽  
James A. Jackson
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Reductase

STUDIES ON THE CYTOCHROME OXIDASE AND OXIDATION PATHWAY IN UREDOSPORES OF WHEAT STEM RUST

1961 ◽  
Vol 39 (5) ◽  
pp. 1131-1148 ◽  
Author(s):  
G. A. White ◽  
G. A. Ledingham
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Reductase Activity ◽  
Oxygen Affinity ◽  
Antimycin A ◽  
Respiratory Enzymes ◽  
Wheat Stem Rust ◽  
Malic Dehydrogenase ◽  
Cytochrome C Reductase

Electron transport to oxygen in a particulate fraction from uredospores of Puccinia graminis var. tritici occurs through a series of carriers similar to those of other fungi and higher plants.Experiments with various enzyme inhibitors and measurements of the oxygen affinity of respiration have shown that cytochrome oxidase mediates the final step in the sequence of electron transfer. The enzyme was localized in a fraction sedimenting at 20,000 g and was typically inhibited by cyanide, azide, and CO-dark, the latter inhibition being light-reversible. Other enzymes present were succinic-cytochrome c reductase, DPNH- and TPNH-cytochrome c reductase, dye reductase, malic dehydrogenase, isocitric dehydrogenase, and glycerol-1-phosphate dehydrogenase. Particulates failed to oxidize DPNH unless an electron acceptor was added. An increase in the activity of several of the respiratory enzymes was noted upon spore germination.Succinic-cytochrome c reductase was only partially sensitive to Antimycin A, HOQNO, and the naphthoquinone, SN 5949. These compounds markedly inhibited a labile portion of the DPNH-cytochrome c reductase activity but had little effect on the stable activity remaining in aged particles. Menadione, but not vitamin K1, stimulated electron transfer. Antimycin A and SN 5949 virtually blocked spore respiration suggesting a "Slater-type" factor in the intact pathway of oxidation.

Effect of prolonged cold exposure on components of the electron transport system

1960 ◽  
Vol 198 (4) ◽  
pp. 740-744 ◽  
Author(s):  
John P. Hannon
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Transport System ◽  
Cold Exposure ◽  
Liver Tissue ◽  
Succinic Dehydrogenase ◽  
Electron Transport System ◽  
Malic Dehydrogenase ◽  
Cytochrome C Reductase

The effect of 3–4 weeks exposure to 5° ± 1°C on the activity of enzymes associated with the electron transport system of rat liver and gastrocnemius muscle was investigated. The enzymes included lactic, succinic and malic dehydrogenase, DPNH-cytochrome c reductase and cytochrome oxidase. Cold exposure led to increased activities on the part of succinic and malic dehydrogenase and cytochrome oxidase. Muscle tissue exhibited a greater response in these components than liver tissue. Lactic dehydrogenase and DPNH-cytochrome c reductase activities were unaffected by cold exposure in either liver or muscle. Thyroxine, 2,4-dinitrophenol, phosphate and hexokinase-glucose stimulated the activity of succinic dehydrogenase activities of liver tissue, with hexokinase-glucose producing the greatest effect. The degree of stimulation by these agents was the same, however, for tissue from cold exposed animals as it was for controls. It was concluded that the increased tissue oxygen consumption in the cold-acclimatized rat was attributable to at least three mechanisms: a) an increased enzyme concentrations; b) a stimulation of latent enzyme activity; and c) an uncoupling of oxidative phosphorylation.

Succinate-cytochrome c reductase, cytochrome oxidase and aldolase activities of denervated rat skeletal muscle

1959 ◽  
Vol 196 (2) ◽  
pp. 465-466 ◽  
Author(s):  
George R. Hearn
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Muscle Fiber ◽  
Total Activity ◽  
Protein Nitrogen ◽  
Cytochrome C Reductase ◽  
Male Wistar Rats ◽  
Succinate Cytochrome C Reductase ◽  
The Right ◽  
Denervated Muscles

Young adult male Wistar rats with an average beginning weight of 294 gm had a segment of the right sciatic nerve removed. The nonoperated left leg served as a control. Succinate-cytochrome c reductase, cytochrome oxidase and aldolase activities, total RNA-P, total DNA-P and total protein were determined for both the denervated and control gastrocnemii muscles. The results for the enzymatic activities were expressed in terms of unit activity and total activity. The denervated muscles had significantly less enzymatic activity, RNA-P, wet weight and protein content ( P <0.02). The losses apparently occurred in the cytoplasmic portion of the muscle fiber. However, this loss was not revealed histologically in the cross section of the muscle fiber. Expression of the results on the basis of unit protein, nitrogen or RNA-P did not significantly alter the results.

scholarly journals The Cox3p assembly module of yeast cytochrome oxidase

2014 ◽  
Vol 25 (7) ◽  
pp. 965-976 ◽  
Author(s):  
Chen-Hsien Su ◽  
Gavin P. McStay ◽  
Alexander Tzagoloff
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Nuclear Genome ◽  
Nuclear Gene ◽  
Gene Products ◽  
Alternative Pathways ◽  
Cytochrome C Reductase ◽  
Respiratory Complex

Yeast cytochrome oxidase (COX) was previously inferred to assemble from three modules, each containing one of the three mitochondrially encoded subunits and a different subset of the eight nuclear gene products that make up this respiratory complex. Pull-down assays of pulse-labeled mitochondria enabled us to characterize Cox3p subassemblies that behave as COX precursors and contain Cox4p, Cox7p, and Cox13p. Surprisingly, Cox4p is a constituent of two other complexes, one of which was previously proposed to be an intermediate of Cox1p biogenesis. This suggests that Cox4p, which contacts Cox1p and Cox3p in the holoenzyme, can be incorporated into COX by two alternative pathways. In addition to subunits of COX, some Cox3p intermediates contain Rcf1p, a protein associated with the supercomplex that stabilizes the interaction of COX with the bc1 (ubiquinol-cytochrome c reductase) complex. Finally, our results indicate that although assembly of the Cox1p module is not contingent on the presence of Cox3p, the converse is not true, as none of the Cox3p subassemblies were detected in a mutant blocked in translation of Cox1p. These studies support our proposal that Cox3p and Cox1p are separate assembly modules with unique compositions of ancillary factors and subunits derived from the nuclear genome.

scholarly journals STUDIES ON THE MECHANISM OF HYDROGEN TRANSPORT IN ANIMAL TISSUES

1943 ◽  
Vol 26 (5) ◽  
pp. 443-455 ◽  
Author(s):  
V. R. Potter ◽  
H. G. Albaum
Keyword(s):  
Alkaline Phosphatase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Cytochrome Oxidase ◽  
Adenosine Triphosphatase ◽  
Succinic Dehydrogenase ◽  
Hydrogen Transport ◽  
Animal Tissues ◽  
Cytochrome C Reductase ◽  
Enzyme Systems

1. The effect of ribonuclease on various enzyme systems was studied as one approach to the problem of whether or not these enzymes are contained in macromolecules of ribonucleoprotein nature in protoplasm. 2. Ribonuclease inhibited CoI-cytochrome c reductase, succinic dehydrogenase, and cytochrome oxidase, all of which require cytochrome c in order to function. Ribonuclease did not act on cytochrome c. 3. Ribonuclease did not inhibit urease, xanthine oxidase, catalase, alkaline phosphatase, or adenosine triphosphatase under the conditions employed. 4. It was suggested that ribonuclease acted sterically by preventing contact between cytochrome c and its activating centers. 5. It was suggested that the enzymes inhibited may be contained in a ribonucleoprotein of macromolecular dimensions but that the enzymes not inhibited are not necessarily excluded from such a complex by the data presented. 6. Further evidence against the Szent-Györgyi theory of hydrogen transport was presented and discussed.

scholarly journals ANALYTICAL FRACTIONATION OF HOMOGENATES FROM CULTURED RAT EMBRYO FIBROBLASTS

1974 ◽  
Vol 63 (2) ◽  
pp. 383-401 ◽  
Author(s):  
Paul Tulkens ◽  
Henry Beaufay ◽  
André Trouet
Keyword(s):  
Plasma Membrane ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Equilibrium Density ◽  
Acid Hydrolases ◽  
Rat Embryo ◽  
Cytochrome C Reductase ◽  
Inosine Diphosphatase ◽  
Embryo Fibroblasts ◽  
Nadh Cytochrome

Homogenates of cultured rat embryo fibroblasts have been assayed for acid phosphatase, N-acetyl-ß-glucosaminidase, cathepsin D, acid deoxyribonuclease, cytochrome oxidase, NADH cytochrome c reductase, 5'-nucleotidase, inosine diphosphatase, acid pyrophosphatase, neutral pyrophosphatase, esterase, catalase, cholesterol, and RNA. The validity of the assay conditions was checked. Neutral pyrophosphatase is a readily soluble enzyme. Acid hydrolases, except acid pyrophosphatase, are particle-bound enzymes, which exhibit a high degree of structural latency. They are activated and solubilized in a parallel fashion by mechanical treatments and tensio-active agents. Catalase is also particle-bound and latent; activating conditions stronger than those for hydrolases are required to activate the enzyme. Acid pyrophosphatase, 5'-nucleotidase and inosine diphosphatase are firmly particle-bound, but not latent; they are not easily solubilized. In differential and isopycnic centrifugation, the latent hydrolases, cytochrome oxidase and catalase dissociate largely from each other; this suggests the occurrence of lysosomes and peroxisome-like structures besides mitochondria. The distribution patterns of 5'-nucleotidase and cholesterol are largely similar; digitonin influences their equilibrium density to the same extent; these two constituents are thought to be related to the plasma membrane. Inosine diphosphatase and acid pyrophosphatase are also partially associated with the plasma membrane, although some part of these enzymic activities probably belongs to other structures. NADH cytochrome c reductase is associated partly with the endoplasmic reticulum, partly with mitochondria.

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