Thermally induced gelation of squid (Illex argentinus) actomyosin. Influence of sexual maturation stage

The biochemical properties and the characteristics of heat-induced gelation of actomyosin from mature and immature squid were investigated. Both Mg2+- ATPase activity and reduced viscosity values of actomyosin showed no signif icant differences between mature and immature squids. A lower content of my osin heavy chain and a higher content of a 160 kDa component were observed in the SDS-PAGE 10% pattern of actomyosin from immature specimens. Gelation of both actomyosins at 10 mg mL(-1) protein concentration was optimal at 8 0 degrees C and pH 6.0. The highest rigidity was reached at 0.25 M KCl with actomyosin from both mature and immature squids. Irrespective of the heati ng temperature, ionic strength, and pH condition, the rigidity of mature sq uid actomyosin gel was greater than that of immature squid. Scanning electr on micrographs of gels obtained with actomyosin from mature squids showed a better tridimensional structure than those of immature squids.