Physico‐chemical and enzymatic studies on acetylated protein isolates from faba beans (Vicia faba L.)

Abstract

AbstractSelected physico‐chemical properties of a faba bean protein isolate before and after being acetylated have been investigated using analytical ultracentrifugation, SE‐ and RP‐HPLC, viscometry and hydrophobicity measurements using fluorescence probe techniques. The time course of relative chymotryptic hydrolysis rates was followed by means of the TNBS method and RP‐HPLC analysis.The extensive decrease of the 11 S and 7 S protein components of the isolate in favour of a low molecular weight 2 S component after exhaustive acetylation is the proof of the dissociated state of the highly modified derivatives. Both the viscometric measurement and the study of proteolysis breakdown give arguments for a rather unfolded state both of the unmodified and the modified protein isolates. The course of relative chymotryptic hydrolysis rate points to a successive transition from a globular state into a more unfolded one depending on the degree of acetylation. Both the viscometric data and the hydrophobicity measurements revealed a conformational transition at about 60% N‐acetylation. This level of modification corresponds to that where a sharp increase of OH‐acetylation takes place.