Quantification of cholesterol-metabolizing P450s CYP27A1 and CYP46A1 in neural tissues reveals a lack of enzyme-product correlations in human retina but not human brain.

ABSTRACT: Cytochrome P450 enzymes (CYP or P450) 46A1 and 27A1 play important roles in cholesterol elimination from the brain and retina, respectively, yet they have not been quantified in human organs because of their low abundance and association with membrane. On the basis of our previous development of a multiple reaction monitoring (MRM) workflow for measurements of low-abundance membrane proteins, we quantified CYP46A1 and CYP27A1 in human brain and retina samples from four donors. These enzymes were quantified in the total membrane pellet, a fraction of the whole tissue homogenate, using ¹⁵N-labled recombinant P450s as internal standards. The average P450 concentrations/mg of total tissue protein were 345 fmol of CYP46A1 and 110 fmol of CYP27A1 in the temporal lobe, and 60 fmol of CYP46A1 and

SUBMITTER: Liao WL 

PROVIDER: S-EPMC3064498 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature