Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The luminescent properties of metal-free, tin(IV) and zinc(II) cytochromes c have been used to characterize the interaction of cytochrome c with mitochondria and cytochrome oxidase. Diminution in the fluorescence yields of tin and zinc cytochrome c occur when these derivates bind to cytochrome oxidase or mitochondria. Based upon spectral overlap and quantum yield, the distance between the porphyrin rings of cytochrome a and cytochrome c is estimated according to Forster theory to be in the neighborhood of 3.5 nm. Measurements of the polarized emission of metal-free 'porphyrin' cytochrome c when bound to oriented layers of cytochrome c oxidase indicate that the porphyrin is bound obliquely to the plane of the oxidase layers with an angle of about 70 degrees C from heme plane to membrane plane. It is proposed that these data have significance for elucidation of electron transfer mechanisms.
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PMID:Metal-free and metal-substituted cytochromes c. Use in characterization of the cytochrome c binding site. 20 55

1. A polarographic assay of superoxide (O2--) dismutase (EC 1.15.1.1) activity is described, in which the ability of the enzyme to inhibit O2---dependent sulphite oxidation, initiated by xanthine oxidase activity, is measured. The assay was used in a study of the intracellular distribution of superoxide dismutase in rat liver. Both cyanide-sensitive cupro-zinc dismutase (92% of the total activity) and cyanide-insensitive mangano-dismutase (8%) were measured. 2. Rat liver homogenates contained both particulate (16%y and soluble (84%) dismutase activity. The particulate activity contained both types of dismutase, whereas nearly all the soluble dismutase was a cupro-zinc enzymes. The distribution pattern of mangano-dismutase was similar to that of cytochrome oxidase and glutamate dehydrogenase, indicating that the enzyme was probably present exclusively in the mitochondria. 3. Superoxide dismutase activity in the heavy-mitochondrial (M) fraction was latent and was activated severalfold and largely solubilized by sonication. Treatment of the M fraction with digitonin or a hypo-osmotic suspending medium indicated that most of the cupro-zinc dismutase was located in the mitochondrial intermembrane space, whereas the mangano-enzyme was located in the inner-membrane and matrix space. 4. A small amount of dismutase activity appeared to be present in the nuclei and microsomal fraction, but little or no activity in the lysosomes or peroxisomes. 5. The results are discussed in relation to the intracellular location of known O2---generating enzymes, the possible role of superoxide dismutase activity in intracellular H2O2 formation, and to current views on the physiological function of the enzyme.
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PMID:Polarographic assay and intracellular distribution of superoxide dismutase in rat liver. 81 Jan 38

The trachea of guinea-pigs was stained as a whole-mount preparation with the zinc iodide-osmium technique. A distinct class of nerve endings was observed associated with the tracheal muscle. The endings, issued from myelinated fibres of the vagus nerve via the recurrent laryngeal nerve, are distributed on either side of the midline and ventral to the tips of cartilages. They are interpreted as afferent nerve endings that may correspond to slow adapting stretch receptors identified by physiological studies. Each nerve contributes predominantly, but not exclusively, to the receptors of the ipsilateral side. There are 120-180 receptors along the full length of the guinea-pig trachea, their density being higher at the cranial end. The receptors are variable in size and structural complexity, and, to some extent, also in spatial orientation, but distinct subtypes are not recognizable. Receptors of similar morphology and distribution are found also in the rat trachea. The receptors can also be visualized with a cytochrome oxidase method for nerve endings, but they do not stain with immunohistochemistry for the neuropeptides substance P, calcitonin gene-related peptide, vasointestinal polypeptide and neurotensin.
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PMID:Afferent nerve endings in the tracheal muscle of guinea-pigs and rats. 171 Dec 97

Zinc sulfate-enriched lactic acid lactobacterin was used in the combined treatment of 23 children with celiac disease, aged from 1 to 10 years. A group of 23 children with celiac disease who received lactic acid lactobacterin without zinc were used as control. The patients treated with lactobacterin containing zinc showed a higher increase in body mass, total protein and zinc levels in the blood serum and elevated activity of metalloenzymes-ceruloplasmin and cytochrome oxidase.
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PMID:[The efficacy of the use of lactic acid lactobacterin enriched with zinc in the treatment of patients with celiac disease]. 179 43

The structural comparison of copper-containing proteins has provided a new dimension to the relationships suggested by sequence similarities. Ryden (1988) summarized the putative relationships, suggesting that a primordial single-domain cupredoxin evolved into the multidomain copper oxidases. The structures have revealed the fact that the differences reside primarily in insertions and deletions at junctions between secondary-structure elements. The mechanism of evolution (e.g., integration of new sequences into regions not essential to the Greek key fold) remains unknown. Which of the properties of a cupredoxin fold are necessary for function is the subject of site-directed mutagenesis studies. Can two of the ligands be interchanged (e.g., the upstream histidine and partially answered by the multidomain copper oxidase structure. The Tyr-Cys-Thr sequence in plastocyanin (in which threonine is a member of the hydrogen-bonding pair) is homologous with the His-Cys-His sequence in ascorbate oxidase. In the latter electron transfer is believed to flow from the type I copper (bound by the cysteine) to the trinuclear cluster, probably via these histidine residues. Hence, one might infer that the tyrosine and threonine have some role in electron transfer. Tyr-83 has been previously implicated in NMR studies as a primary site of electron transfer. The multi-copper protein structures have revealed interesting new features. The extra coppers are bound at domain interfaces, and can be single metals or the novel trinuclear cluster, depending on the availability of liganding histidines. A structural model of ceruloplasmin suggests that it will have at least two type I sites and, possibly, a third type I site such as stellacyanin (no methionine ligand), as well as a binding site for a trinuclear cluster. The similarity of the sequences of N2O reductases and a domain of cytochrome oxidase to the sequences of proteins with known structures suggests that these, too, will have Greek key domains. Galactose oxidase and hemocyanin do not have Greek key folds in their functional domains, although each does have a Greek key domain. The need for a Greek key fold remains obscure. The apoproteins are clearly stable without metals; there are examples other than immunoglobulins of Greek key folds. So far copper seems to be found in a very limited subset of structures; other chapters in this volume show that zinc, for example, has a much wider variety of environments in proteins, as does iron. It may be that the copper-containing Greek key proteins represent a very small evolutionary niche.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Copper protein structures. 179 5

The aim of this study was to evaluate the effect of lead and excess zinc on the adaptation of mitochondria from skeletal muscles to physical effort. Rats were intoxicated once a week for 12 weeks by subcutaneous injection of the solution containing 2 mg Zn+2 and/or 3 mg Pb2+ per kg of body weight. During the last 6 weeks, 6 times weekly, rats performed endurance training which involved swimming 15 minutes daily with additional load of 5% of the body weight. The activities of isocitrate (ICD), malate (SDH), succinate (MDH) dehydrogenases, cytochrome oxidase (COX) and protein content (PM) were determined in the mitochondrial fractions obtained from the soleus muscle (ST fibres), and from the superficial (FTb fibres) and deep (FTa fibres) parts of the gastrocnemius muscle. In the control group (C), which was injected with saline, higher activities of ICD and MDH were obtained in FTa and FTb fibres than in the ST fibres. SDH and COX had higher activities in FTa and ST compared to FTb fibres. Zinc treatment (Zn) caused diminution of ICD, SDH and COX activities in ST fibres. Lead intoxication (Pb) resulted in a decrease of MDH activity in all fibre types, and in a decrease of SDH activity in ST fibres. Simultaneous action of zinc and lead produced an increase in ICD activity and diminution of COX activity in FTb fibres. It also resulted in an increase of SDH and decrease of COX activity in ST fibres. These results suggest that the ST fibres are more susceptible to disturbances of adaptation to physical exercise caused by zinc and lead. There are no signs of uniform antagonism between zinc and lead action in the processes under investigation.
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PMID:The activity of mitochondrial enzymes in the muscles of rats subjected to physical training and subchronical intoxication with lead and zinc. 248 52

1. A number of dietary sugars are known to mediate the effects of copper deficiency. The effects of lactose (compared with sucrose) and a dietary Cu deficiency on hepatic and cardiac antioxidant enzyme activities and tissue mineral element status were investigated in the rat. 2. Groups (n 6) of male weanling Wistar rats were provided ad lib. with deionized water and diets containing sucrose (580 g/kg) or sucrose and lactose (387 g/kg and 193 g/kg respectively) with either control (12.0 mg/kg) or deficient (1.5 mg/kg) quantities of Cu for 77 d. 3. Animals consuming the low-Cu diets exhibited significantly decreased tissue Cu levels (P less than 0.01), hepatic and cardiac cytochrome c oxidase (EC 1.9.3.1, CCO) activities (P less than 0.01 and P less than 0.001 respectively) and hepatic Cu-zinc superoxide dismutase (EC 1.15.1.1, CuZnSOD) activity (P less than 0.05). The low-Cu diets also significantly decreased cardiac manganese superoxide dismutase (EC 1.15.1.1, MnSOD), catalase (EC 1.11.1.6) and glutathione peroxidase (EC 1.11.1.9, GSH-Px) activities (P less than 0.01, P less than 0.05 and P less than 0.001 respectively). 4. Hepatic Mn was significantly increased in both lactose-fed (P less than 0.001) and Cu-deficient (P less than 0.01) animals. These increases were unrelated to hepatic MnSOD activity. Cardiac Zn was significantly (P less than 0.01) increased in Cu-deficient animals. 5. Lactose feeding resulted in significantly increased cardiac CCO activity (P less than 0.001) but significantly decreased hepatic CuZnSOD (P less than 0.05), catalase (P less than 0.01) and GSH-Px (P less than 0.001) activities. 6. The activities of lactose dehydrogenase (EC 1.1.1.27, LDH) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6PDH) were found to be significantly (P less than 0.05 and P less than 0.01 respectively) increased in Cu-deficient animals and G6PDH activity was significantly (P less than 0.01) decreased as a result of lactose consumption. 7. The observed changes in antioxidant enzyme activities associated with both Cu deficieny and lactose consumption may have important implications for the development of free radical mediated cell damage. However, no significant differences in either hepatic or cardiac levels of thiobarbituric acid reactive substances, a measure of lipid peroxidation, were found.
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PMID:Effects of copper deficiency on hepatic and cardiac antioxidant enzyme activities in lactose- and sucrose-fed rats. 253 51

A number of preparations of cytochrome oxidase have been analyzed for metals by energy dispersive X-ray fluorescence spectrometry. The EPR characteristics, the peptide compositions, the protein and phospholipid contents as well as the catalytic constants of the samples have also been determined. It is confirmed that the enzyme functional unit contains three copper atoms and one zinc atom in addition to two iron atoms. On the basis of the parameters determined for the different samples it is suggested that a high catalytic activity of a preparation can be correlated to a number of other analytical characteristics.
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PMID:Analytical characterization of cytochrome oxidase preparations with regard to metal and phospholipid contents, peptide composition and catalytic activity. 254 68

The role of zinc in beef heart cytochrome c oxidase has been studied by using x-ray absorption spectroscopy, zinc depletion and secondary structure predictions of subunits of beef heart cytochrome c oxidase. The stoichiometry of zinc in cytochrome oxidase has been determined in 35 different preparations and found to be one-half of copper (Cu:Zu = 2:1). Zinc is tightly bound to this enzyme and cannot be removed by dialysis against EDTA. However, zinc could be partially (up to 50%) depleted by treating the enzyme with either dipicolinic acid or by trypsin digestion. This partial depletion of zinc does not change the O2 uptake rate. X-ray absorption spectroscopy shows that the atom is in a distorted tetrahedral environment with mostly sulfur ligands. Since subunit VIa removed by the digestion removes about one-half the zinc, a possible binding site involves the two S sites present in that subunit with an appropriate folding in a structural role.
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PMID:On the environment of zinc in beef heart cytochrome c oxidase: an x-ray absorption study. 284 29

The steady-state kinetics of Pseudomonas aeruginosa cytochrome oxidase were studied. Reduced cytochrome c551 and azurin from the same bacteria were used as the electron-donating substrates, while dioxygen served as the electron acceptor. Oxidized cytochrome c551 and azurin exhibited product inhibition of the reaction. However, apo-azurin and azurin derivatives in which the copper was substituted by the redox-inert ions Ni2+, Co2+, Cd2+ and Zn2+, did not show any effect on the kinetics. These observations implied that complex formation between the substrates or the products and the enzyme is not a rate-limiting step and is not the cause for product inhibition. The integrated rate law for a reaction scheme in which we assumed that complex formation was not rate limiting was fitted to the complete reaction traces. The results suggested that it is the low thermodynamic driving force, expressed in the small differences in redox potential between the substrates and heme c of the enzyme, which cause the observed product inhibition.
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PMID:Pseudomonas aeruginosa cytochrome oxidase. Product inhibition by low thermodynamic driving force. 302 48


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