Cholate effects on all-trans-retinyl palmitate hydrolysis in tissue homogenates: solubilization of multiple kidney membrane hydrolases.
Retinyl ester hydrolysis was observed in the absence of cholate in homogenates of rat lung, liver, kidney, intestine, and testes. Eighty-four percent of the activity in kidney was membrane-associated. The kidney microsomal fraction contained 19% of the total activity and was the only subcellular fraction that had increased specific activity relative to the homogenate (about 1.5-fold). In contrast, the cytosol was the only fraction that was decreased in specific activity (about 3-fold). Cholate (18 mM), reportedly required to observe hydrolysis of all-trans-retinyl esters by rat liver preparations, was not obligatory for activity in kidney homogenates or microsomes. The microsomal activity was solubilized efficiently and with a twofold increase in specific activity by the synthetic detergent 1-S-octyl-beta-D-thioglucopyranoside. Gel-permeation chromatography of the solubilizate suggested that at least two pools of activity existed, with molecular weights in the ranges 70-95 and 30-40 kDa. Neither hydrolyzed cholesteryl oleate. Both were more active in hydrolyzing retinyl palmitate than trioleoylglycerol. The higher mass pool had decreased trioleoylglycerol hydrolase activity relative to the solubilizate. Anion-exchange chromatography separated the lower mass pool into two major peaks. A major peak, distinct from the two peaks observed with the lower mass pool, was observed upon anion-exchange chromatography of the higher mass pool. These data demonstrate that multiple retinyl ester hydrolases, more efficient at hydrolyzing retinyl esters than cholesteryl esters and triacylglycerol, occur in a retinoid target tissue.
Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214.
J L
JL
Napoli
E B
EB
Pacia
G J
GJ
Salerno
D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003902:Detergents / Q000494:pharmacology; D004224:Diterpenes; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D009928:Organ Specificity; D051381:Rats; D000084562:Retinyl Esters; D012995:Solubility; D013347:Subcellular Fractions / Q000201:enzymology; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000378:metabolism
D002793:Cholic Acids; D003902:Detergents; D004224:Diterpenes; D007527:Isoenzymes; D000084562:Retinyl Esters; C022521:retinol-palmitate esterase; D014801:Vitamin A; C014794:retinol palmitate; D002265:Carboxylic Ester Hydrolases; D019826:Cholic Acid