title: The environment of cytochrome P-450 in testicular microsomes.
abstract: The effects of trypsin, phospholipase A, and chymotrypsin on NADPH-cytochrome c reductase and cytochrome P-450 of microsomes from cryptorchid mouse testes and liver were compared. Trypsin released both enzymes almost completely from testis microsomes, while it readily released only NADPH-cytochrome c reductase from liver microsomes. Chymotrypsin alone, even under conditions where 30-40% of the microsomal protein was hydrolyzed, had little effect on localization or activity of either enzyme in either tissue. Phospholipase A destroyed cytochrome P-450 in testicular microsomes but had little effect on this enzyme in hepatic microsomes or on NADPH-cytochrome c reductase in either preparation. When, however, the microsomes were incubated with chymotrypsin in the presence of a detergent, the effects were similar to those of trypsin alone; testicular cytochrome P-450 was destroyed, while hepatic cytochrome P-450 was only slightly solubilized, and NADPH-cytochrome c reductase from both types of microsomes was both solubilized and activated. From these results we conclude that arginyl and/or lysyl bonds may play a significant role in the junction between the hydrophobic region of the membrane and the anchor region of the reductase molecule and that cytochrome P-450 of testicular microsomes is more superficially located in the lipid bilayer than is hepatic microsomal cytochrome P-450.
mesh_terms: D000818:Animals; D002918:Chymotrypsin / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008861:Microsomes / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D013737:Testis / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology
chemical_list: D003577:Cytochrome P-450 Enzyme System; D009245:NADH Dehydrogenase; D010741:Phospholipases A; D002918:Chymotrypsin; D014357:Trypsin