Biomaterial Database

Identification and functional characterization of leukotriene B4 20-hydroxylase of human polymorphonuclear leukocytes. 1985

R J Soberman, and T W Harper, and R C Murphy, and K F Austen

A single reaction product was formed during the incubation of 1.5 microM (5S,12R)-dihydroxy-6,14-cis-8,10-trans-[3H]icosatetraenoic acid (leukotriene B4, LTB4) for 30 min at 37 degrees C in 10 mM potassium phosphate buffer (pH 7.5) with 100 microM NADPH and the 150,000 X g supernatant of sonicated human polymorphonuclear leukocytes (PMN). The reaction product exhibited the same mobility on reversed-phase HPLC (RP-HPLC) and TLC as standard 20-hydroxy-LTB4 (20-OH-LTB4). When the omega-oxidation product of [3H]LTB4 was eluted from a Sep-Pak, resolved by RP-HPLC, and analyzed by GC/MS, its structure was determined to be solely 20-OH-LTB4. The Km of the 20-hydroxylase for [3H]LTB4 at its optimal pH of 7.5 was 0.22 +/- 0.08 microM (mean +/- SD, n = 4) and the Vmax was 48 +/- 11 pmol/min X mg of protein (mean +/- SD, n = 4). When the concentration of [3H]LTB4 was fixed at 1.5 microM, the Km for NADPH was 1.01 +/- 0.59 microM (mean +/- SD, n = 3). The location in the 150,000 X g supernatant of the LTB4 20-hydroxylase distinguishes it from the cytochrome P-450 system of liver, lung, and kidney microsomes and from the NADPH oxidase-cytochrome b-245 system of the human PMN. The LTB4 20-hydroxylase is either a unique cytochrome P-450 or other monooxygenase.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007975	Leukotriene B4	The major metabolite in neutrophil polymorphonuclear leukocytes. It stimulates polymorphonuclear cell function (degranulation, formation of oxygen-centered free radicals, arachidonic acid release, and metabolism). (From Dictionary of Prostaglandins and Related Compounds, 1990)	5,12-HETE,5,12-diHETE,LTB4,Leukotriene B,Leukotriene B-4,Leukotrienes B,5,12 HETE,5,12 diHETE,B-4, Leukotriene,Leukotriene B 4
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
D003577	Cytochrome P-450 Enzyme System	A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.	Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D003600	Cytosol	Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.	Cytosols
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006899	Mixed Function Oxygenases	Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.	Hydroxylase,Hydroxylases,Mixed Function Oxidase,Mixed Function Oxygenase,Monooxygenase,Monooxygenases,Mixed Function Oxidases,Function Oxidase, Mixed,Function Oxygenase, Mixed,Oxidase, Mixed Function,Oxidases, Mixed Function,Oxygenase, Mixed Function,Oxygenases, Mixed Function
D000072470	Cytochrome P450 Family 4	A cytochrome P450 enzyme family that includes members which function in the metabolism of FATTY ACIDS, especially ARACHIDONIC ACIDS and their derivatives.	CYP4 Enzymes,CYP4 Family