Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytoplasmic membranes of Bacillus subtilis, grown in complex medium containing glucose, were fractionated into three membrane subfractions [light band (1.155 - 1.158 g/cm3); medium band (1.181 - 1.183 g/cm3); heavy band (1.21 - 1.25 g/cm3)] by sucrose density gradient centrifugation. Among these subfractions, the light and medium bands consisted mainly of membranes but the heavy band consisted of an irregular arrangement or aggregate of small globular protein components of 5 - 8 nm in diameter. We named this H-protein. H-protein formed trilamellar unit membrane structure when combined with lipid. In pulse-labeling and pulse-chase experiments with radioactive leucine, it was found that H-protein consisted of the newest membrane protein synthesized in the cells and the label incorporated into H-protein was shifted into light and medium band of the membranes during the chase. Cytochromes were not found in H-protein. However, when H-protein was incubated with haem alpha and protohaem, these compounds were incorporated into the apoproteins of the cytochromes present in H-protein and form cytochromes a and b. Cytochromes were also formed in H-protein which were isolated from the cells grown in the presence of haemin (haemin-grown H protein). Succinate dehydrogenase activity was increased about 4-fold by combining H-protein or haemin-grown H protein with lipid. H-protein had no cytochrome oxidase activity; however, haemin-grown H protein was found to have some of the activity and this was increased about 4-fold by combining the protein with lipid. Haemin-grown H protein was also found to form succinate: cytochrome c oxidoreductase when combined with lipid and vitamin K2. On the other hand, succinate oxidase was required for the addition of lipid, vitamin K2 and cytochrome c. NADH oxidase was also found in haemin-grown H protein and was activated about 9-fold in constituted reaction systems. Vesicles formed by haemin-grown H protein and lipid, could accumulate alanine and proline by addition of NADH or reduced phenazine methosulfate. Alanine and proline was also accumulated into the vesicles when transport energy was supplied as a membrane potential introduced by K+-diffusion via valinomycin. These results would indicate that H-protein contains the apoprotein of cytochromes, and a carrier involved in the active transport of alanine and proline.
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PMID:Isolation and characterization of hydrophobic proteins (H proteins) in the membrane fraction of Bacillus subtilis. Involvement in membrane biosynthesis and the formation of biochemically active membrane vesicles by combining H proteins with lipid. 18 52

The role of heme in the synthesis of cytochrome c oxidase has been investigated in the mold Neurospora crassa. Iron-deficient cultures of the mold have low levels of cytochrome oxidase and delta-aminolevulinate dehydratase, the latter being the rate-limiting enzyme of the heme-biosynthetic pathway in this organism. Addition of iron to the iron-deficient cultures results in an immediate increase in the levels of delta-aminolevulinate dehydratase followed by an increase in the rate of heme synthesis and cytochrome oxidase levels. The rate of precursor labeling of the mitochondrial subunits of cytochrome oxidase is decreased preferentially under conditions of iron deficiency and addition of iron corrects this picture. Exogenous hemin addition which prevents iron-mediated induction of delta-aminolevulinate dehydratase also inhibits the increase in the activity of cytochrome oxidase and the enhanced precursor labeling of the mitochondrial subunits of cytochrome oxidase. Protein synthesis on mitoribosomes measured in vivo and in vitro is decreased under conditions of heme deficiency. Hemin addition in vitro to mitochondrial lysates prepared from heme-deficient mycelia restores a near normal rate of protein synthesis. It is concluded that heme is required for the optimal rate of translation on mitoribosomes.
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PMID:Role of heme in the synthesis of cytochrome c oxidase in Neurospora crassa. 625 61

White, D. C. (Rockefeller Institute, New York, N.Y.). Respiratory systems in hemin-requiring Haemophilus species. J. Bacteriol. 85:84-96. 1963.-If grown in Levinthal's medium or in proteose peptone medium with excess hemin, Haemophilus influenzae, H. aegyptius, and H. canis (H. haemoglobinophilus) form an electron-transport system consisting of six cytochromes and two respiratory flavoproteins. In proteose peptone, these species can greatly modify the composition of their electron-transport complex. With anaerobic incubation in the presence of nitrate, they produce increased amounts of cytochrome c(1) and the cytochrome oxidases a(1) and o. This anaerobic pattern is greatly exaggerated by growth under carbon monoxide, in which case large concentrations of cytochrome oxidase are produced. In the presence of the inhibitor secobarbital or of growth-limiting amounts of hemin, intermediate amounts of cytochromes and respiratory flavoproteins are formed. When only small amounts of hemin are present, these species grow but form no detectable cytochrome system. Catalase is the only hemoprotein found. Under these conditions, the addition of glucose induces the formation of a lactate oxidase flavoprotein if the system is incubated aerobically. This cytochromeless state also occurs when these species are grown in KCN or anaerobically without nitrate and with excess hemin. The ability of these species to modify the composition of the electron-transport system strongly suggests that this function unit is formed from individual components. Hemin-requiring Haemophilus species have a hemin-sparing compensatory mechanism that allows growth under conditions under which hemin-independent Haemophilus species will not grow.
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PMID:Respiratory systems in the hemin-requiring Haemophilus species. 1400 Feb 93