EFFECT OF CHARCOAL DELIPIDIZATION TREATMENT OF BETA-LACTOGLOBULIN ON KINETICS OF BETA-LACTOGLOBULIN RETINOIC ACID COMPLEX AND ITS TRYPTIC HYDROLYSIS/

Studies were carried out to evaluate the effect of charcoal treatment on beta-lactoglobulin with respect to retinoic acid binding and trypti c digestion on the protein/ligand complex. It was shown that charcoal delipidization treatment did not have much effect on the beta-lactoglo bulin/retinoic acid binding parameters such as dissociation constant ( Kd) and apparent molar binding ratio (n). The Kd of charcoal treated b eta-lactoglobulin/retinoic acid complex and native beta-lactoglobulin/ retinoic acid complex were 2.10 x 10(-6) M and 2.80 x 10(-6) M, respec tively. The n of charcoal treated beta-lactoglobulin/retinoic acid com plex was 0.92, which was similar to the n of native beta-lactoglobulin /retinoic acid complex (0.99). Charcoal treatment did not have a signi ficant effect on tryptic digestion of beta-lactoglobulin. However, the binding of retinoic acid to beta-lactoglobulin slowed down the trypti c hydrolysis of the protein. About 80% of the retinoic acid bound char coal treated and native beta-lactoglobulin remained undigested at the end of 4 h digestion period. On the other hand, more than 90% of the p rotein (native and charcoal treated) was digested in the same time fra me.