コイ筋原繊維たんばく質の冷凍変性に及ぼす糖の保護効果

抄録

To study the protective effect of sugar on denaturation of myofibrillar protein, carp myofibrils suspension in a medium containing 0.16M KCI, 40 mM Tris-buffer of pH 7.5, 6.5 or 5.8, and various concentrations of sucrose or sorbitol (0-1.0M) was stored at-20°C and the change in Ca-ATPase activity was measured as a function of the lapse of storage time (for 100 days).
The inactivation of Ca-ATPase was found to proceed in two first-order steps: an early fast decrease (k_{D ??} ), followed by a slow decrease (k_{D ??} ). For the case of slow inactivation at pH 7.5 and with a higher concentration (M) of sugar; however, a slower step could not be distinguished.
The protective effect of sugar on the denaturation of myofibrillar protein during frozen storage was estimated from the slope of linear relation between the logarithm of k_{D ??} and sugar concentration (M).
It was thus found that the protective effect of sugar was enhanced on the denaturation of myofibrillar protein during frozen storage at around pH 7.5. The effect of sucrose was slightly stronger than that of sorbitol upon the addition of the same molarity (mol/l) to the myofibrils suspension.