Metabolism of leukotrienes by L-gamma-glutamyl-transpeptidase and dipeptidase from human polymorphonuclear granulocytes.
Stimulation of human polymorphonuclear granulocytes with the calcium-ionophore A23187 and opsonized zymosan leads to the release of leukotrienes. The cell-free supernatants of the stimulated cells revealed gamma-glutamyl-transpeptidase and dipeptidase activity which induced the metabolism of exogeneously added LTC4 and LTD4 respectively. No glutathione-S-transferase activity was present in the supernatant. In the absence of calcium, no leukotrienes were generated; dipeptidase activity was slowly released and gamma-glutamyl-transpeptidase activity was not detected. By subcellular fractionation, glutathione-S-transferase activity was present in the microsomal and cytosol fractions, and gamma-glutamyl-transpeptidase and dipeptidase were recovered from the granular and microsomal fractions. By equilibrium density-gradient centrifugation, highest dipeptidase activity eluted in the range between 1.18 and 1.22 g/ml; gamma-glutamyl-transpeptidase was present in the range from 1.13 to 1.18 g/ml and 1.20 to 1.22 g/ml; glutathione-S-transferase did not enter the gradient under these conditions. Solubilization of the 100,000 g pellet of homogenized cells with Triton X-100 led to the release of soluble gamma-glutamyl-transpeptidase and dipeptidase enzymes into the supernatant.
Raulf
M
M
Stüning
M
M
König
W
W
D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D004150:Dipeptidases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007975:Leukotriene B4 / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D013189:SRS-A / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
D013189:SRS-A; D007975:Leukotriene B4; D000001:Calcimycin; D005723:gamma-Glutamyltransferase; D004150:Dipeptidases; C038937:dipeptidase