THE EFFECTS OF PH AND BILE-SALTS ON THE BINDING OF MEIQX TO WHEAT BRAN FIBER

The effects of pH and of the bile salts, sodium cholate, chenodeoxycho late, taurocholate, deoxycholate and glycodeoxycholate on the adsorpti on of the heterocyclic aromatic amine mutagen and carcinogen 2-amino-3 ,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) onto wheat bran cell wall material have been examined. The highest binding affinity of MeIQx fo r bran was at pH 5.5. Binding affinity declined more rapidly with pH > 5.5 than with pH < 5.5. Bile salts in solution did not appreciably af fect the binding of MeIQx to bran, but where the bile salts formed a s uspension then the adsorption was reduced. Where precipitation of bile salts occurred then the free concentration of MeIQx was also reduced, indicating that MeIQx binding/immobilisation could be enhanced throug h interaction with bile salts.