title: Leukotriene A5 is a substrate and an inhibitor of rat and human neutrophil LTA4 hydrolase.
abstract: The epoxide 5(S) trans-5,6 oxido, 7,9 trans-11,14,17 cis eicosatetraenoic acid (leukotriene A5) was chemically synthesized and demonstrated to be both a substrate and an inhibitor of partially purified rat and human LTA4 hydrolase. Both rat and human LTA4 hydrolase utilized leukotriene A5 less effectively as a substrate than leukotriene A4. Incubation of leukotriene A5 (10 microM) or leukotriene A4 (10 microM) with rat neutrophils demonstrated formation of 123 pmol LTB5/min/10(7) cells and 408 pmol LTB4/min/10(7) cells respectively. Purified rat neutrophil LTA4 hydrolase incubated with 100 microM leukotriene A5 produced 22 nmol LTB5/min/mg protein and when incubated with 100 microM leukotriene A4 produced 50 nmol LTB4/min/mg protein. Human neutrophil LTA4 hydrolase incubated with 100 microM leukotriene A5 produced 24 nmol LTB5/min/mg protein and when incubated with 100 microM leukotriene A4 produced 52 nmol LTB4/min/mg protein. Leukotriene A5 was an inhibitor of the formation of leukotriene B4 from leukotriene A4 by both the rat and human neutrophil LTA4 hydrolase. Excess leukotriene A5 prevented covalent coupling of [3H] leukotriene A4 to LTA4 hydrolase suggesting inhibition may involve covalent coupling of leukotriene A5 to the LTA4 hydrolase.
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism* / Q000494:pharmacology; D015118:Eicosapentaenoic Acid / Q000031:analogs & derivatives / Q000096:biosynthesis; D004851:Epoxide Hydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D017572:Leukotriene A4; D007975:Leukotriene B4 / Q000096:biosynthesis / Q000031:analogs & derivatives; D009504:Neutrophils / Q000201:enzymology; D051381:Rats
chemical_list: D001095:Arachidonic Acids; D017572:Leukotriene A4; D007975:Leukotriene B4; C040212:leukotriene B5; D015118:Eicosapentaenoic Acid; D004851:Epoxide Hydrolases; C043134:leukotriene A4 hydrolase