GLIADIN MODIFICATIONS CATALYZED BY GUINEA-PIG LIVER TRANSGLUTAMINASE

Wheat gliadins, that are glutamine rich and lysine poor proteins, are good substrates for transglutaminases reactions. This study was conduc ted to determine the efficiency with which guinea pig liver transgluta minase catalyzes transfer and hydrolysis reactions of native and acyla ted gliadins. In all reactions, 35% of the total glutaminyl residues w ere modified. Neutral pH simultaneously enhanced glutaminyl residue hy drolysis and protein cross-linking, while acidic pH reduced the cross- linking reaction. Functional properties of two enzymatically modified gliadins and a chemically deamidated one were tested at neutral pH. A deamidation level of 25-2 7% appeared to be an optimum for the emulsif ication properties. Enzymatically modified gliadin showed better resis tance to coalescence than the chemically deamidated one; a result that probably is related to the presence of high molecular weight polymers .