Nippon Suisan Gakkaishi 65 (5), 886-891 (1999)

Effects of Sodium Gluconate on Thermal Denaturation and Solubilization of Carp Myofibrils*1

Mizue Takeshita,*2 Tooru Ooizumi,*2 Yoshiaki Akahane,*2 and Seishi Takenawa*3

The effects of sodium gluconate (Na-gluconate) on thermal inactivation of Ca-ATPase and solubilization of carp myofibrils were compared with those of sorbitol and sodium chloride (NaCl). Na-gluconate decreased the thermal inactivation rate constant for myofibrillar Ca-ATPase (kD) the same as sorbitol did. On the contrary, NaCl accelerated thermal denaturation of myofibrils. The protective effect (E value) of Na-gluconate on heat-denaturation was considerably larger than that of sorbitol. Although sorbitol had no effect on the solubilization of myofibril, the addition of 0.25-0.30 M Na-gluconate induced a decrease in turbidity of myofibril suspension accompanied by the increase in the amount of extracted protein. Therefore, it was clearly demonstrated that Na-gluconate solubilized myofibrils at higher concentration than NaCl. The measurement of sodium ion concentration in the solution with a sodium ion electrode indicated less electrolytic dissociation degree of Na-gluconate than NaCl, suggesting that the myofibrils solubilizing effect of both compounds corresponded to their ionization degree in the solution.


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