Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Drug
Enzyme
Compound
Query: EC:1.9.3.1 (
cytochrome oxidase
)
8,822
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
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.
...
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.
...
PMID:Respiratory systems in the hemin-requiring Haemophilus species. 1400 Feb 93
