On the Nature of the Streaming Birefringence Observed in the Aqueous Extracts of Squid Muscle-I

1) When squid muscle were repeatedly extracted with 2_??_20 times the amount oof water, streaming birefringence (SB) was observed in the second and the following extracts (Fig. 1).<br>2) When squid muscle were extracted repeatedly the total amount of proteins passing into solution amounted to 55.5 per cent of total proteins. In carp and horse .mackerel muscle, however, the totalextractible proteins was not so much beyond the amount of non-myosins which was to be expected from the literature on the subject (Table 1)<br>3) The amount of water soluble proteins of squid muscle increased with the in crease of the ratio of extracting water to muscle, while those of flat fish and horse mackerel muscle attained a constant value with the increasing ratio (Fig. 2).<br>4) In squid, the amount of non-myosins was as small as one fifth to one third of the water extractible fraction, while in flat fish, horse mackerel, and carp, the .amount of ncn-myosins werefound to coincide roughly with that of the water extra-ctible fraction (Tables 1 and 2).<br>5) If the aqueous extracts of squid muscle were dialysed against distilled water, some of the proteins precipitated on centrifugation. The precipitate from the seconct extract showed SB if it was mixed into an aqueous suspension, while the precipitate of the first extract did not.<br>6) Some of the proteins precipitated out if KCI was added to aqueous extracts. of squid muscle so as to make up mixtures of varying ionic strengths ranging from 0.0005 to 1.0. The relationship of solubility to ionic strength seems to suggest the presence of both myosin proper and actomyosin in the aqueous extracts (Figs. 3 and 4).<br>7) In view of these facts it was suggested that in the case of squid muscle, myosin might be dispersed into the aqueous suspension and give rise to the characteristic SB.<br>The authors wish to express their gratitude to Miss Tomiko ARAI and Mr. Yoshio. Isxiro for their devoted assistance in the experimental work.<br>The authors thank Mrs. Dorothy GILNER who has kindly consented to read overthe manuscript.