Biomaterial Database

Activation of the respiratory burst enzyme from human neutrophils in a cell-free system. Evidence for a soluble cofactor. 1985

L C McPhail, and P S Shirley, and C C Clayton, and R Snyderman

Activation of the respiratory burst in phagocytic cells, an important host defense process, is not yet well understood. We now report the development of a cell-free system for activation of NADPH oxidase, the respiratory burst enzyme, in human neutrophils. Activation was achieved by the addition of arachidonic acid to a postnuclear supernatant (500 g) from disrupted unstimulated cells (no arachidonate, 0.2; with arachidonate, 3.4 nmol superoxide anion/min per mg) and was dependent on both the concentration of arachidonate and on the amount of cellular material present. Activity stimulated by arachidonate appeared to be NADPH oxidase based on a Michaelis constant for NADPH of 32 microM and a pH optimum of 7.0-7.5. Separation of the 500-g supernatant by high speed centrifugation revealed a requirement for both soluble and particulate cofactors. Activation of NADPH oxidase by arachidonate did not occur in the high speed pellet fraction from unstimulated cells but could be restored by the addition of the high speed supernatant. In addition, priming of intact neutrophils with low concentrations of the chemoattractant N-formyl-methionyl-leucyl-phenylalanine or the tumor promoter phorbol myristate acetate replaced the soluble factor requirement for NADPH oxidase activation by arachidonate in the high speed pellet. This cell-free system can now be used to provide further insight into the biochemical basis of priming and the terminal mechanisms involved in the activation of NADPH oxidase.

UI	MeSH Term	Description	Entries
D009247	NADH, NADPH Oxidoreductases	A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.	Oxidoreductases, NADH, NADPH,NADPH Oxidoreductases NADH,Oxidoreductases NADH, NADPH
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
D002474	Cell-Free System	A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)	Cellfree System,Cell Free System,Cell-Free Systems,Cellfree Systems,System, Cell-Free,System, Cellfree,Systems, Cell-Free,Systems, Cellfree
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001095	Arachidonic Acids		Eicosatetraenoic Acids,Acids, Arachidonic,Acids, Eicosatetraenoic
D013347	Subcellular Fractions	Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)	Fraction, Subcellular,Fractions, Subcellular,Subcellular Fraction
D013481	Superoxides	Highly reactive compounds produced when oxygen is reduced by a single electron. In biological systems, they may be generated during the normal catalytic function of a number of enzymes and during the oxidation of hemoglobin to METHEMOGLOBIN. In living organisms, SUPEROXIDE DISMUTASE protects the cell from the deleterious effects of superoxides.	Superoxide Radical,Superoxide,Superoxide Anion
D016718	Arachidonic Acid	An unsaturated, essential fatty acid. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides. It is formed by the synthesis from dietary linoleic acid and is a precursor in the biosynthesis of prostaglandins, thromboxanes, and leukotrienes.	(all-Z)-5,8,11,14-Eicosatetraenoic acid,Arachidonic Acid, (all-Z)-Isomer, 1-(14)C-Labeled,Arachidonic Acid, (all-Z)-isomer, 3H-Labeled,Arachidonic Acid, Ammonium Salt, (all-Z)-Isomer,Arachidonic Acid, Cerium Salt, (all-Z)-Isomer,Arachidonic Acid, Cesium Salt, (all-Z)-Isomer,Arachidonic Acid, Lithium Salt, (all-Z)-Isomer,Arachidonic Acid, Potassium Salt, (all-Z)-Isomer,Arachidonic Acid, Sodium Salt,Arachidonic Acid, Sodium Salt, (all-Z)-Isomer,Arachidonic Acid, Zinc Salt, (all-Z)-Isomer,Sodium Arachidonate,Vitamin F,Arachidonate, Sodium
D019255	NADPH Oxidases	A family of membrane-associated flavoprotein NADPH-dependent oxidoreductases that catalyze the univalent reduction of OXYGEN to create SUPEROXIDES. Structurally, they are characterized by six N-terminal transmembrane ALPHA-HELICES, a FLAVIN-ADENINE DINUCLEOTIDE (FAD)-binding region, and a C-terminal NADPH-binding region. They are expressed primarily by EPITHELIAL CELLS in gut, kidney, colon, and smooth muscle tissues, as well as GRANULOCYTES and function to transfer electrons across membranes to molecular oxygen. Defects in the production of superoxide ions by some NADPH oxidases result in GRANULOMATOUS DISEASE, CHRONIC.	NADPH Oxidase,NAD(P)H Oxidases,NAD(P)H oxidase,Nox Proteins,Oxidase, NADPH,Oxidases, NADPH