凍結乾燥によるコイ筋原繊維タンパク質の変性に対するソルビトールの防止効果

Abstract

To study the preventive effect of sorbitol against denaturation of myofibrillar protein by freeze-drying, carp myofibrils suspension was mixed with various concentrations of sorbitol in a medium containing 0.16M KCl and 40mM Tris-buffer (pH 7.5), and the changes in Ca-ATPase activity were measured as a function of freeze-drying time. The results obtained were as follows: (1) The activity of Ca-ATPase decreased rapidly in the initial 2h freeze-drying and remained at a definite value during the subsequent freeze-drying period. Thus the first rate constant (kD) for inactivation of Ca-ATPase in the early period was estimated. (2) As the log-arithmic value of kD was inversely proportional to the concentration (a) of sorbitol, the protec-tive effect (E) of sorbitol against the denaturation of myofibrillar protein caused by freeze-drying in the presence of a 1 M sorbitol was estimated in the following equation: E=Δlog kD/a(M-1). (3) As there was a proportional relation between the logarithmic value of remaining Ca-ATPase activity after 2h freeze-drying and concentration (a) of sorbitol, another index (R) for evaluation of the preventive effect of sorbitol against the freeze-drying denaturation of myofibrillar protein was devised as R=Δlog A/a(M-1), where A is the relative value of myofidril-lar Ca-ATPase activity after freeze-drying.