Thermally induced gelation of paramyosin from scallop adductor muscle

ABSTRACT:   Thermally induced gelation of paramyosin from scallop smooth adductor muscle was investigated by dynamic rheological measurements under various conditions. The paramyosin thermal gel was produced at pH 6.5 and 7.2 at temperatures above 30°C through a two-step increase in storage (G') and loss (G') moduli; these values were higher than in gels produced from actomyosin at a high temperature. The thermal gel properties were very firm and brittle. In contrast, one main peak of G' was observed during gelation at pH 8.0. The gel produced at pH 8.0 was more transparent and less soluble in a 6 M urea?0.5 M NaCl solution than those formed either at pH 6.5 or 7.2. These differences in the thermal gel properties are presumed to derive from the pH dependence of the gel matrix-forming process, such as oxidative cross-linking between cysteine residues, rather than from the thermal unfolding of the paramyosin molecules. The thermal gelation profile of chymotrypsin-digested paramyosin showed marked depression of G' at high temperature.