Synthesis and applicability of photolabile 7,7-azo analogues of natural bile salt precursors.

Abstract

In an approach to the identification of proteins involved in the side chain degradation of bile salt biosynthesis, the photolabile 7,7-azo derivatives of 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,26-tetrol and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oate were synthesized. All 7,7-azo derivatives were metabolized by intact rat liver and freshly isolated rat hepatocytes in the same manner as the nonphotolabile physiological intermediates, resulting in the formation of the 7,7-azo analogues of cholyltaurine and cholylglycine. Photolysis of all three photolabile derivatives, using a light source with a maximum emission at 350 nm, occurred with a half-life of 2.1 min; their efficacy for photoaffinity labeling was demonstrated by incorporation into rat serum albumin.