Alpha-hydroxylation of lignoceroyl-CoA in rat brain microsomes: involvement of NADPH-cytochrome c reductase and topical distribution.
1. The enzymatic mechanism of the alpha-hydroxylation of lignoceroyl-CoA, an intermediate in the synthesis of hydroxyceramide, was studied. In the presence of NADPH, sphingosine and microsomes from 20-day-old rat brain, 14C from [1-14C]lignoceroyl-CoA was incorporated into hydroxyceramide. 2. The alpha-hydroxylation of lignoceroyl-CoA in rat brain microsomes was strongly inhibited by a rabbit anti-immunoglobulin G which was prepared against rat liver microsomal NADPH-cytochrome c reductase. However, anti-immunoglobulin G against cytochrome b5 did not inhibit the alpha-hydroxylase activity. 3. The alpha-hydroxylation activity was more sensitive to trypsin treatment than was NADPH-cytochrome c reductase in rat brain microsomes. This indicates that either alpha-hydroxylase itself or an unknown factor essential in alpha-hydroxylation is highly exposed to the surface of brain microsomes.
Shigematsu
H
H
Daiichi College of Pharmaceutical Sciences, Fukuoka, Japan.
Hisanari
Y
Y
Kishimoto
Y
Y
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology / Q000378:metabolism*; D002518:Ceramides / Q000096:biosynthesis; D002848:Chromatography, DEAE-Cellulose; D003429:Cross Reactions; D015786:Cytochromes b5 / Q000302:isolation & purification; D006900:Hydroxylation; D007106:Immune Sera; D005779:Immunodiffusion; D008297:Male; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism*; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism; D009251:NADPH-Ferrihemoprotein Reductase / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D014357:Trypsin
D000214:Acyl Coenzyme A; D002518:Ceramides; D007106:Immune Sera; C018582:lignoceroyl-coenzyme A; D015786:Cytochromes b5; D009251:NADPH-Ferrihemoprotein Reductase; D014357:Trypsin