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Hemeprotein

About: Hemeprotein is a research topic. Over the lifetime, 4943 publications have been published within this topic receiving 207015 citations.


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01 Mar 1986
TL;DR: The Cytochrome P450 and the Metabolism and Bioactivation of Arachidonic Acid and Eicosanoids in Plants and the Diversity and Importance of Microbial Cytochromes P450 are studied.
Abstract: Recent Work: Models and Mechanisms of Cytochrome P450 Action (J.T. Groves, Y. Han). Comparison of the Peroxidase Activity of Hemoproteins and Cytochrome P450 (L.J. Marnett, T.A. Kennedy). Structurally Defined Bacterial Enzymes: Twentyfive Years of P450cam Research: Mechanistic Insights into Oxygenase Catalysis (E.J. Mueller et al.). Structural Studies on Prokaryotic Cytochromes P450 (T.L. Poulos et al.). Bacterial P450s: Structural Similarities and Functional Differences (J.A. Peterson, S.E. GrahamLorence). Structures and Mechanisms of Membranebound P450 Enzymes: Structures of Eukaryotic Cytochrome P450 Enzymes (C. von Wachenfeldt, E.F. Johnson). NADPH Cytochrome P450 Reductase and Its Structural and Functional Domains (H.W. Strobel et al.). Oxygen Activation and Reactivity (P.R. Ortiz de Montellano). Inhibition of Cytochrome P450 Enzymes (P.R. Ortiz de Montellano, M.A. Correia). Regulatory Mechanisms and Physiological Roles of Cytochrome P450: Induction of Cytochrome P450 Enzymes That Metabolize Xenobiotics (J.P. Whitlock, Jr., M.S. Denison). Hormonal Regulation of Liver Cytochrome P450 Enzymes (D.J. Waxman, K.H. Chang). Regulation of Steroidogenic and Related P450s (N. Kagawa, M.R. Waterman). Cytochrome P450 and the Metabolism of Arachidonic Acid and Oxygenated Eicosanoids (J.H. Capdevila et al.). Human Cytochrome P450 Enzymes (F.P. Guengerich). Heme Thiolate Proteins Different from Cytochromes P450 Catalyzing Monooxygenations (D. Mansuy, J.P. Renaud). Appendixes. Index.

2,381 citations

Journal ArticleDOI
24 Aug 1995-Nature
TL;DR: The crystal structure at 2.8 Å resolution of the four protein subunits containing cytochrome c oxidase from the soil bacterium Paracoccus denitrificans, complexed with an antibody Fv fragment, is described and mechanisms for proton pumping are discussed.
Abstract: The crystal structure at 2.8 A resolution of the four protein subunits containing cytochrome c oxidase from the soil bacterium Paracoccus denitrificans, complexed with an antibody Fv fragment, is described. Subunit I contains 12 membrane-spanning, primarily helical segments and binds haem a and the haem a3-copper B binuclear centre where molecular oxygen is reduced to water. Two proton transfer pathways, one for protons consumed in water formation and one for 'proton pumping', could be identified. Mechanisms for proton pumping are discussed.

1,926 citations

Journal ArticleDOI
TL;DR: In this review recent findings on heme oxygenase are highlighted and it is shown that the enzyme activity is inhibited in vivo for extended periods subsequent to binding of Zn- and Sn- protoporphyrins.
Abstract: In biological systems oxidation of heme is carried out by two isozymes of the microsomal heme oxygenase, HO-1 and HO-2. HO-1 is the commonly known heme oxygenase, the activity of which can be induced by up to 100-fold in response to a wide variety of stimuli (metals, heme, hormones, etc.). HO-2 was only recently discovered, and the isozyme appears to be uninducible. The two forms are products of two different genes and differ in their tissue expression. The primary structure of HO-1 and an HO-2 fragment of 91 amino acid residues show only 58% homology, but share a region with 100% secondary structure homology. This region is believed to be the catalytic site. Most likely, HO-1 gene is regulated in the same manner as metallothione in the gene. HO-1 has a heat shock regulatory element, and possibly many promoter elements, which bind to respective inducers and cause transcription of the gene. In vivo induction of HO-1 activity in the liver is accompanied by decreases in the total P-450 levels and, in a reconstituted system, cytochrome P-450b heme can be quantitatively converted to biliverdin by HO-1 and HO-2. The enzyme activity is inhibited in vivo for extended periods subsequent to binding of Zn- and Sn- protoporphyrins. This property appears useful for the suppression of bilirubin production. The metalloporphyrins, however, are not innocuous and cause major disruptions in cellular metabolism. In this review recent findings on heme oxygenase are highlighted.

1,711 citations

Journal ArticleDOI
25 Aug 1995-Science
TL;DR: The high resolution three-dimensional x-ray structure of the metal sites of bovine heart cytochrome c oxidase is reported, suggesting a dinuclear copper center with an unexpected structure similar to a [2Fe-2S]-type iron-sulfur center.
Abstract: The high resolution three-dimensional x-ray structure of the metal sites of bovine heart cytochrome c oxidase is reported. Cytochrome c oxidase is the largest membrane protein yet crystallized and analyzed at atomic resolution. Electron density distribution of the oxidized bovine cytochrome c oxidase at 2.8 A resolution indicates a dinuclear copper center with an unexpected structure similar to a [2Fe-2S]-type iron-sulfur center. Previously predicted zinc and magnesium sites have been located, the former bound by a nuclear encoded subunit on the matrix side of the membrane, and the latter situated between heme a3 and CuA, at the interface of subunits I and II. The O2 binding site contains heme a3 iron and copper atoms (CuB) with an interatomic distance of 4.5 A; there is no detectable bridging ligand between iron and copper atoms in spite of a strong antiferromagnetic coupling between them. A hydrogen bond is present between a hydroxyl group of the hydroxyfarnesylethyl side chain of heme a3 and an OH of a tyrosine. The tyrosine phenol plane is immediately adjacent and perpendicular to an imidazole group bonded to CuB, suggesting a possible role in intramolecular electron transfer or conformational control, the latter of which could induce the redox-coupled proton pumping. A phenyl group located halfway between a pyrrole plane of the heme a3 and an imidazole plane liganded to the other heme (heme a) could also influence electron transfer or conformational control.

1,319 citations

Journal ArticleDOI
09 Dec 1988-Science
TL;DR: A model is proposed in which a ligand-dependent conformational change in a heme protein accounts for the mechanism by which hypoxia as well as cobalt and nickel stimulate the production of Epo.
Abstract: Erythropoietin (Epo), the hormone that stimulates red blood cell production, is synthesized in the kidney and liver in response to hypoxia. The human hepatoma cell line Hep3B regulates its production of Epo in a physiologic manner. Either hypoxia or cobalt chloride markedly increases expression of Epo mRNA as well as production of biologically active and immunologically distinct Epo protein. New protein synthesis is required before the induction of increased levels of hypoxia- or cobalt-induced Epo mRNA. Hypoxia, cobalt chloride, and nickel chloride appear to stimulate Epo production through a common pathway. The inhibition of Epo production at low partial pressures of oxygen by carbon monoxide provides evidence that a heme protein is integrally involved in the oxygen-sensing mechanism. This hypothesis is further supported by the finding that when heme synthesis is blocked, hypoxia-, cobalt-, and nickel-induced Epo production are all markedly inhibited. A model is proposed in which a ligand-dependent conformational change in a heme protein accounts for the mechanism by which hypoxia as well as cobalt and nickel stimulate the production of Epo.

1,003 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202356
202282
202139
202048
201951
201850