イカ筋肉の新収縮性蛋白-コイのアクトミオシンとの比較的研究

Abstract

1) To prove the assumption that the streaming birefringence (SB) observed in the aqueous extracts of squid muscle is due to the dissolving-out of actomyosin or an actomyosin-like protein, the streaming birefringent protein was separated as a concentrated solution by precipitating it through dialysis against 0.3M KCl. Then the properties of the protein were compared experimentally with those of carp actomyosin. 2) Whereas SB of carp actomyosin, on addition of ATP, showed a very similar response to that reported on rabbit actomyosin (Fig. 2), the streaming birefringent protein of squid behaved itself in a similar but distinct way, if Mg ion was present (Fig. 3). 3) Both carp actomyosin and the streaming birefringent protein of squid showed a typical superprecipitation (Figs. 5 and 6, Tables 2 and 3). 4) From salting-in curves, it was found that the used preparation of the streaming birefringent protein of squid contained one or two minor components, while that of carp actomyosin was homogeneous (Figs. 7). 5) It was inferred that, in the aqueous extracts of squid muscle, an amount of actomyosin-like protein is dissolved which has the functional properties of the contractile proteins. However, for some differences from actomyosins of rabbit and carp were found, and for these differences may be shared by mollusks, it was proposed to call this protein “M-actomyosin”.