Protease-catalyzed formation of plastein products and some of their properties

Mechanisms of plastein formation, and prospective food and nutraceutical applications of the peptide aggregates

“…Van Hofsten and Lalasidis [48] reported the absence of high molecular weight product in whey and fish protein-derived plastein, whereas other studies reported the formation of low- and high-molecular weight peptide complexes during plastein reaction [8]. Based on these findings, transpeptidation was proposed to be partially responsible for plastein formation [17], [20], [54].…”

“…Plastein was first thought to be a resynthesized protein based on the decrease in free amino nitrogen content and absence of precipitate formation when inactivated protease was used [7], [48]. However, it was also thought that the precipitates are formed as a result of denaturation of high molecular weight substances in the hydrolysis product [7], [25].…”

Enzymatic Modification of Fish Frame Protein Isolate

“…The method used for plastein assay was developed by Fugimaki et al (1977), Yamashita et al (1970) and later modified by Hofsten and Lalasidis (1976). Plastein synthesis.…”

Food Protein Nutrient Improvement by Protease at Reduced Water Activity

“…In the hydrolytic reactions, catalyzed by serine-proteases, a transitory acyl-enzyme intermediate transfers the acyl group to water. However, in enzymatic peptide synthesis, the acyl group is transferred to other nucleophiles, such as the amino groups amino acids, resulting in synthesis by a transpeptidation mechanism, as postulated for the plastein reaction (Tsai et al, 1972;Hofsten and Lalasidis, 1976;Fujimaki et al, 1977;Edwards and Shipe, 1978). Other researcher (Determann et al, 1965;Yamashita et aZ., 1973), suggested that plastein synthesis occurs by a condensation mechanism, as a reversal of the usual hydrolytic reaction.…”