Biomaterial Database

Subcellular distribution of superoxide dismutases in human neutrophils. Influence of myeloperoxidase on the measurement of superoxide dismutase activity. 1977

R F Rest, and J K Spitznagel

We have identified two distinct pools of superoxide dismutase in fractions of human peripheral neutrophils obtained by the isopycnic fractionation of homogenates of the latter with linear sucrose gradients. Superoxide dismutase activity, observed with polyacrylamide gels impregnated with Nitro Blue Tetrazolium, was present in: (1) the mitochondrial fraction [density (rho) 1.169g/ml], containing the high-molecular-weight KCN-resistant enzyme, and (2) the cytoplasm fraction, containing the low-molecular-weight KCN-sensitive enzyme. Superoxide dismutase activity, observed with a quantitative assay involving cytochrome c, was present in: (1) the mitochondria, (2) the cytoplasm, and (3) the azurophil-granule fractions (rho=1.206 and 1.222g/ml). No substantial enzyme activity was observed in specific-granule fractions (rho=1.187g/ml) or in the membranous fraction (rho=1.136g/ml) in either assay. The apparent superoxide dismutase activity observed in the azurophil granules with the cytochrome c assay was attributable not to true superoxide dismutase but to myeloperoxidase, an enzyme found solely in the azurophil granules. In the presence of H(2)O(2), human neutrophil myeloperoxidase oxidized ferrocytochrome c. Thus, in the cytochrome c assay for superoxide dismutase, the oxidation of ferrocytochrome c by myeloperoxidase mimicked the inhibition of reduction of ferricytochrome c by superoxide dismutase. When myeloperoxidase was removed from azurophilgranule fractions by specific immuno-affinity chromatography, both myeloperoxidase and apparent superoxide dismutase activities were removed. It is concluded that there is no detectable superoxide dismutase in either the azurophil or specific granules of human neutrophils. Mitochondrial superoxide dismutase, 15% of the total dismutase activity of the cells, occurred only in fractions of density 1.160g/ml, where isocitrate dehydrogenase and cytochrome oxidase were also observed.

UI	MeSH Term	Description	Entries
D007521	Isocitrate Dehydrogenase	An enzyme of the oxidoreductase class that catalyzes the conversion of isocitrate and NAD+ to yield 2-ketoglutarate, carbon dioxide, and NADH. It occurs in cell mitochondria. The enzyme requires Mg2+, Mn2+; it is activated by ADP, citrate, and Ca2+, and inhibited by NADH, NADPH, and ATP. The reaction is the key rate-limiting step of the citric acid (tricarboxylic) cycle. (From Dorland, 27th ed) (The NADP+ enzyme is EC 1.1.1.42.) EC 1.1.1.41.	NAD Isocitrate Dehydrogenase,Isocitrate Dehydrogenase (NAD+),Isocitrate Dehydrogenase-I,Dehydrogenase, Isocitrate,Dehydrogenase, NAD Isocitrate,Isocitrate Dehydrogenase I,Isocitrate Dehydrogenase, NAD
D008297	Male		Males
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D009195	Peroxidase	A hemeprotein from leukocytes. Deficiency of this enzyme leads to a hereditary disorder coupled with disseminated moniliasis. It catalyzes the conversion of a donor and peroxide to an oxidized donor and water. EC 1.11.1.7.	Myeloperoxidase,Hemi-Myeloperoxidase,Hemi Myeloperoxidase
D009504	Neutrophils	Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.	LE Cells,Leukocytes, Polymorphonuclear,Polymorphonuclear Leukocytes,Polymorphonuclear Neutrophils,Neutrophil Band Cells,Band Cell, Neutrophil,Cell, LE,LE Cell,Leukocyte, Polymorphonuclear,Neutrophil,Neutrophil Band Cell,Neutrophil, Polymorphonuclear,Polymorphonuclear Leukocyte,Polymorphonuclear Neutrophil
D009580	Nitroblue Tetrazolium	Colorless to yellow dye that is reducible to blue or black formazan crystals by certain cells; formerly used to distinguish between nonbacterial and bacterial diseases, the latter causing neutrophils to reduce the dye; used to confirm diagnosis of chronic granulomatous disease.	Nitro-BT,Nitrotetrazolium Blue,Tetrazolium Nitroblue,Blue, Nitrotetrazolium,Nitroblue, Tetrazolium,Tetrazolium, Nitroblue
D002500	Centrifugation, Isopycnic	A technique used to separate particles according to their densities in a continuous density gradient. The sample is usually mixed with a solution of known gradient materials and subjected to centrifugation. Each particle sediments to the position at which the gradient density is equal to its own. The range of the density gradient is usually greater than that of the sample particles. It is used in purifying biological materials such as proteins, nucleic acids, organelles, and cell types.	Isopycnic Centrifugation
D002846	Chromatography, Affinity	A chromatographic technique that utilizes the ability of biological molecules, often ANTIBODIES, to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Bioaffinity,Immunochromatography,Affinity Chromatography,Bioaffinity Chromatography
D003486	Cyanides	Inorganic salts of HYDROGEN CYANIDE containing the -CN radical. The concept also includes isocyanides. It is distinguished from NITRILES, which denotes organic compounds containing the -CN radical.	Cyanide,Isocyanide,Isocyanides
D003574	Cytochrome c Group	A group of cytochromes with covalent thioether linkages between either or both of the vinyl side chains of protoheme and the protein. (Enzyme Nomenclature, 1992, p539)	Cytochromes Type c,Group, Cytochrome c,Type c, Cytochromes