Bile Salt Binding to Serum Components. Taurocholate Incorporation into High-Density Lipoprotein Revealed by Photoaffinity Labelling

Publisher Website
Google Scholar
Abstract
Photoaffinity labeling of human serum albumin with the sodium salts of (3.beta.-azido-7.alpha.,12.alpha.-dihydroxy-5.beta.-cholan-24-oyl)-2-amino[2-3H(N)]ethanesulfonic acid, (7,7-azo-3.alpha.,12.alpha.-dihydroxy-5.beta.-cholan-24-oyl)-2-amino[2-3H(N)]ethanesulfonic acid and (11.zeta.-azido-12-oxo-3.alpha.,7.alpha.-dihydroxy-5.beta.-cholan-24-oyl)-2-amino[2-3H(N)]ethanesulfonic acid resulted, in each case, in a considerable covalent incorporation of radioactivity into the protein. Photoaffinity labeling of whole serum, obtained from fasting test persons, revealed with all 3 photolabile derivatives of taurocholate at the physiological concentration of 2.1 .mu.M, the incorporation of radioactivity not only into albumin but also into high-density lipoprotein (HDL), as demonstrated by density gradient centrifugation and by immunological characterization. The bulk of radioactivity incorporated into HDL by photoaffinity labeling of whole serum was associated with the lipids. Only 10-20% of the label was covalently bound to apolipoproteins, predominantly to the apolipoproteins A-I and A-II. The interaction of taurocholate with HDL was confirmed by density gradient centrifugation using 14C-labeled taurocholate. The interaction of taurocholate with HDL may be physiologically significant.

This publication has 21 references indexed in Scilit: