Coenzyme A derivatives of bile acids—chemical synthesis, purification, and utilization in enzymic preparation of taurine conjugates

Abstract

Synthesis of the coenzyme A derivatives of bile acids by the mixed anyhydride method results in a product that is contaminated by unreacted CoASH and bile acid. These compounds can be purified by Sephadex LH-20 chromatography. In each case, the purified product is free of starting materials and exhibits an equimolar ratio of bile acid, coenzyme A, and thioester bond. Millimolar extinction coefficients were calculated for these compounds as A259 nm, 15.03 ± 0.58; A232 nm, 7.60 ± 0.17; and A232 nm for the thioester bond, 4.12 ± 0.17. These CoA derivatives were hydrolyzed in strongly alkaline solution, but were stable at physiologic temperature and pH. Utilization of these compounds in the enzymic preparation of taurine conjugates of bile acids indicated 94% activity. These purified CoA derivatives may be useful in studying the enzymic conjugation of bile acids.

Keywords

• bile acid conjugation
• coenzyme A thioesters
• enzymatic activity
• ultraviolet extinction coefficients