Conjugation of cholic acid with taurine and glycine by rat liver peroxisomes

We have previously shown that rat liver peroxisomes catalyze conversion of 3α,7α,12α-trihydroxy-5β-cholestanoic acid into cholic acid as the CoA-ester (1). In the present work it is shown that addition of taurine or glycine to the reaction mixture, choloyl-CoA is further converted to taurocholic or glycocholic acid, respectively. The identity of these products was verified by fast atom bombardment — mass spectrometry. The peroxisomal fraction catalyzed conjugation of cholic acid with taurine (22.3 nmol × mg −1 × h −1 ) or glycine (18.6 nmol × mg −1 × h −1 ) at rates twice those observed with the microsomal fraction. The results indicate that conjugation of newly formed bile acids may be an important function of liver peroxisomes.