メバチマグロおよびキハダマグロ冷凍肉ミオシンの比較について

概要

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1) The Ca2+-ATPase activity (μmoles Pi per min per mg of protein) of bigeye tuna myosin was 0.10-0.25, and that of yellowfin tuna myosin was 0.70-0.85. The activity determination was carried out at 25°C in a reaction medium containing 50 mM KCl, 5mM CaCl2, 25mM Tris buffer (pH 7.0), and 1 mM ATP. 2) The ATP-sensitivity of synthetic actomyosin was also measured; it was 45-80 for bigeye tuna actomyosin, and 80-102 for yellowfin tuna actomyosin. 3) On ultracentrifugation, the sedimentation pattern of yellowfin tuna myosin showed a hypersharp peak characteristic of the myosin monomer (S20w=5.3S at protein concentration of 2.7 mg/ml). The pattern of bigeye tuna myosin, on the other hand, showed at least two peaks: a fast moving boundary presumably of myosin dimer, and a slow moving one of myosin monomer. 4) The elution profile on DEAE-sephadex A-50 chromatography was investigated. The profile obtained with yellowfin tuna myosin preparations was similar to that obtained with myosin monomer. On the other hand, the elution pattern of bigeye tuna myosin preparations showed a peak at void volume, probably of highly aggregated myosin, a peak of myosin dimer, and a peak of myosin monomer; the latter two peaks overlapping. It appears, therefore, that bigeye tuna myosin is somewhat denatured during the freezing and storage (-20°C) process.
公益社団法人日本水産学会の論文