Localization of leukotriene D4-metabolizing metalloenzyme on the cell surface of human neutrophils.
The localization of leukotriene D4-metabolizing enzyme on the cell surface was examined using human neutrophils. Intact neutrophils rapidly converted leukotriene D4 to leukotriene E4. However, when neutrophils were modified chemically by diazotized sulfanilic acid, a poorly permeant reagent which inactivates cell surface enzymes selectively, the leukotriene D4-metabolizing activity of neutrophils decreased significantly without any inhibition of the cell viability or marker enzymes of cytosol, granules, microsome and mitochondria. The leukotriene D4-metabolizing enzyme activity of the membrane fraction was inhibited by modification to the same extent as that of Mg2+-dependent ATPase, a cell-surface marker enzyme. Among various enzyme inhibitors examined, a metal chelator, o-phenanthroline, strongly suppressed the leukotriene D4-metabolizing activity of intact neutrophils and the o-phenanthroline-inactivated enzyme activity was fully reactivated by Co2+, Mn2+ and Zn2+. These results would suggest that some metalloenzyme located on the cell surface is involved in the conversion of leukotriene D4 to leukotriene E4 by neutrophils.
D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D004150:Dipeptidases / Q000378:metabolism*; D006168:Guinea Pigs; D006801:Humans; D017999:Leukotriene E4; D009504:Neutrophils / Q000201:enzymology*; D013189:SRS-A / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000378:metabolism*
D013189:SRS-A; D017999:Leukotriene E4; D004150:Dipeptidases; C036942:leukotriene D4 dipeptidase