TY - JOUR
T1 - Evidence for two enzymatic pathways for omega-oxidation of docosanoic acid in rat liver microsomes
AU - Sanders, Robert-Jan
AU - Ofman, Rob
AU - Valianpour, Fredoen
AU - Kemp, Stephan
AU - Wanders, Ronald J. A.
PY - 2005
Y1 - 2005
N2 - We studied the omega-oxidation of docosanoic acid (C22:0) in rat liver microsomes. C22:0 and 22-hydroxy-docosanoic acid (omega-hydroxy-C22:0) were used as substrates, and the reaction products were analyzed by electrospray ionization mass spectrometry. In the presence of NADPH, omega-oxidation of C22:0 produced not only the hydroxylated product, omega-hydroxy-C22:0, but also the dicarboxylic acid of C22:0, docosanedioic acid (C22:0-DCA). When rat liver microsomes were incubated with omega-hydroxy-C22:0 in the presence of either NAD+ or NADPH, C22:0-DCA was formed readily. Formation of C22:0-DCA from either C22:0 or omega-hydroxy-C22:0 with NADPH as cofactor was inhibited strongly by miconazole and disulfiram, whereas no inhibition was found with NAD+ as cofactor. Furthermore, omega-oxidation of C22:0 was reduced significantly when molecular oxygen was depleted. The high sensitivity toward the more specific cytochrome P450 inhibitors ketoconazole and 17-octadecynoic acid suggests that hydroxylation of C22:0 and omega-hydroxy-C22:0 may be catalyzed by one or more cytochrome P450 hydroxylases belonging to the CYP4A and/or CYP4F subfamily. This study demonstrates that C22:0 is a substrate for the omega-oxidation system in rat liver microsomes and that the product of the first hydroxylation step, omega-hydroxy-C22:0, may undergo further oxidation via two distinct pathways driven by NAD+ or NADPH
AB - We studied the omega-oxidation of docosanoic acid (C22:0) in rat liver microsomes. C22:0 and 22-hydroxy-docosanoic acid (omega-hydroxy-C22:0) were used as substrates, and the reaction products were analyzed by electrospray ionization mass spectrometry. In the presence of NADPH, omega-oxidation of C22:0 produced not only the hydroxylated product, omega-hydroxy-C22:0, but also the dicarboxylic acid of C22:0, docosanedioic acid (C22:0-DCA). When rat liver microsomes were incubated with omega-hydroxy-C22:0 in the presence of either NAD+ or NADPH, C22:0-DCA was formed readily. Formation of C22:0-DCA from either C22:0 or omega-hydroxy-C22:0 with NADPH as cofactor was inhibited strongly by miconazole and disulfiram, whereas no inhibition was found with NAD+ as cofactor. Furthermore, omega-oxidation of C22:0 was reduced significantly when molecular oxygen was depleted. The high sensitivity toward the more specific cytochrome P450 inhibitors ketoconazole and 17-octadecynoic acid suggests that hydroxylation of C22:0 and omega-hydroxy-C22:0 may be catalyzed by one or more cytochrome P450 hydroxylases belonging to the CYP4A and/or CYP4F subfamily. This study demonstrates that C22:0 is a substrate for the omega-oxidation system in rat liver microsomes and that the product of the first hydroxylation step, omega-hydroxy-C22:0, may undergo further oxidation via two distinct pathways driven by NAD+ or NADPH
U2 - https://doi.org/10.1194/jlr.M400510-JLR200
DO - https://doi.org/10.1194/jlr.M400510-JLR200
M3 - Article
C2 - 15716582
SN - 0022-2275
VL - 46
SP - 1001
EP - 1008
JO - Journal of Lipid Research
JF - Journal of Lipid Research
IS - 5
ER -