Vitamin A Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin A, including details on retinol, benefits, dosage, supplements, deficiency, information.

Influence of binding of sodium dodecyl sulfate, all-trans-retinol, palmitate, and 8-anilino-1-naphthalenesulfonate on the heat-induced unfolding and aggregation of beta-lactoglobulin B.

Considine T, Patel HA, Singh H, Creamer LK

Fonterra Research Centre, Private Bag 11 029, Palmerston North, New Zealand.

Heat treatment of bovine beta-lactoglobulin B (beta-LG) causes it to partially unfold and aggregate via hydrophobic association and intra- and interprotein disulfide bonds. The first stage, which involves a "loosening" of the native structure, is influenced by the environmental conditions, such as pressure, pH, and added solutes. In the present study, four potential beta-LG ligands [palmitate, sodium dodecyl sulfate (SDS), 8-anilino-1-naphthalenesulfonate (ANS), and all-trans-retinol (retinol)] were added to beta-LG solutions prior to heat treatment for 12 min at temperatures between 40 and 93 degrees C. The extent of the changes in secondary and tertiary structures, unfolding, and aggregation at 20 degrees C were determined by circular dichroism, fluorescence, and alkaline- and SDS-polyacrylamide gel electrophoresis (PAGE). Both palmitate and SDS stabilized the native structure of beta-LG against heat-induced structural flexibility, subsequent unfolding, and denaturation. Retinol was less effective, probably because of its lower affinity for the calyx-binding site, and ANS did not stabilize beta-LG, suggesting that ANS did not bind strongly in the calyx. It was also noted that holding a beta-LG solution with added SDS or ANS promoted the formation of a hydrophobically associated non-native dimer.

Published 13 April 2005 in J Agric Food Chem, 53(8): 3197-205.
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