EFFECT OF THIOLATION ON THE PHYSICOCHEMICAL AND FUNCTIONAL-PROPERTIES OF BOVINE SERUM-ALBUMIN

The effects of the attachment of homocysteine residues, to either 16 or 21 amino groups of bovine serum albumin (BSA), on the physicochemical and functional properties were studied. Both thiolated protein derivatives had a lower isoelectric point, hydrophobicity and alpha-helix conformation compared with the native protein. Polyacrylamide gel electrophoresis indicated that modification of the proteins resulted in a mixture of products. Thiolation impaired the whipping and gelling properties of bovine serum albumin but there was little change in the emulsification properties. It was concluded that increasing the available sulphydryl groups did not promote disulphide/sulphydryl interchange reactions leading to enhanced functional properties; on the contrary, the blocking of amino groups was instrumental in impairing the whipping and gelling properties.