2-ARYLPROPIONYL-COA EPIMERASE - PARTIAL PEPTIDE SEQUENCES AND TISSUE LOCALIZATION

The R-enantiomers of 2-arylpropionic acids (2-APAs) such as ibuprofen (IBU) exhibit the phenomenon of species- and substrate-dependent metab olic chiral inversion. Only R-enantiomers are activated to acyl-CoA-th ioesters by an acyl-CoA-synthetase via an adenylate intermediate. The acyl-CoA-thioesters are substrates for an epimerase, which is responsi ble for chiral inversion. A 42 kDa epimerase from the cytosolic fracti on of rat livers was isolated and purified to homogeneity. Polyclonal antibodies were raised against the epimerase in rabbits. The anti-epim erase antibodies were used for affinity column chromatography to separ ate homogeneous protein for amino acid sequence analysis. Sequence dat a analysis of 3 internal peptide sequences showed 50% and more homolog y with regions of enzymes involved in fatty acid metabolism. The polyc lonal anti-epimerase antibodies were used to analyze the tissue distri bution of the protein in guinea pigs and rats by Western blot analysis . Furthermore, the correlation of inversion enzyme activity ill variou s tissues under comparable incubation conditions and cross-reactivity in Western blot analysis was investigated.