魚類筋原繊維Ca-ATPaseの温度安定性と環境適応

概要

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Thermostabilities of 40 species of fish myofibrls were systematically studied by using ARRHENIUS plots of first order rate constants (κD) for inactivation of myofirillar Ca-ATPase. The comparison of the linear ARRHENIUS plots suggested that there is a relationship between the thermostability of fish myofibrils and the environmental temperature at which the species lives. The enthalpy of activation (ΔH≠), the entropy of activation (ΔS≠), and the free energy of activation (ΔG≠) for the reaction at 25°C were estimated from the corresponding ARRHENIUS plots as 80-100 kcal/mol, 170-240 e.u., and 25-27 kcal/mol for warm water fishes and 50-70 kcal/mol, 100-160 e.u., and 23-25 kcal/mol for cold water fishes. All of these parameters for the inactivation increased from cold water to warm water habitates, though the proprtions of ΔH≠ as well as ΔS≠ varied considerably among species and ΔG≠ values varied somewhat. In addition, a positive correlation betwwen ΔG≠, ΔH≠ or ΔS≠ and the environmental temperature was demonstrated for the fish species studied. These results, suggest that the differences in thermostability of fish myofibrillar Ca-ATPase were caused by physiological adaptation of this enzyme to the environment at the molecular level.
日本水産學會の論文