title: Prostaglandin endoperoxide E2 isomerase is dissociated from prostaglandin endoperoxide synthetase in the renal cortex.
abstract: The rate of arachidonic acid metabolism by prostaglandin (PG) endoperoxide synthetase by the rabbit renal cortex (approximately 200 pmol/mg of protein/min) is very slow compared to medulla (approximately 2000 pmol/mg/min). However, by using PGH2 as a substrate and limiting reaction times, we were able to directly measure the endoperoxide-dependent PGE2 isomerase and found that both the cortex and medulla possess high levels of this activity (approximately pmol/mg/min). The PG endoperoxide E2 isomerase is dependent on reduced glutathione, but not cysteine, and is inactivated by p-hydroxymercuribenzoate or boiling. Thus, the renal medulla appears to exhibit an efficient coupling of cyclooxygenase and PG endoperoxide E2 isomerase, whereas the cortex has a vast excess of endoperoxide-dependent enzyme.
mesh_terms: D000818:Animals; D019746:Intramolecular Oxidoreductases; D007535:Isomerases / Q000302:isolation & purification* / Q000378:metabolism; D007672:Kidney Cortex / Q000201:enzymology*; D007679:Kidney Medulla / Q000201:enzymology; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D009928:Organ Specificity; D000071876:Prostaglandin-E Synthases; D011451:Prostaglandin-Endoperoxide Synthases / Q000302:isolation & purification* / Q000378:metabolism; D011817:Rabbits
chemical_list: D011451:Prostaglandin-Endoperoxide Synthases; D007535:Isomerases; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases