The effect of freezing on the denaturation of actomyosin prepared from carp dorsal muscle was investigated by measurement of Ca²⁺-ATPase and by solubilities.
Factors involved in the denaturation, i.e., salt (KCl) concentration, pH of the solution and presence of sugar compounds, were tested.
1. The denaturation of actomyosin Ca²⁺-ATPase by freezing accelerated as the protein concentration decreased below 4 mg/ml, while it proceeded at a uniform rate as protein concentration increased above 5mg/ml.
2. To obtain a uniform protective effect of sugar compounds on the denaturation of actomyosin Ca²⁺-ATPase by freezing, it was necessary to add sugar compounds at 20 times the actomyosin content (w/w).
3. On freezing in higher KCl concentration (ref. 0.6M KCl), sorbitol exerted a remarkable protective effect and sucrose, a lesser effect on the denaturation of actomyosin Ca²⁺-ATPase. On freezing in lower KCl concentration (ref. 0.13M KCl), remarkable protective effects by sucrose as well as sorbitol were observed.
4. In comparing the protective effect of some sugar compounds on the denatura-tion of actomyosin Ca²⁺-ATPase in 0.6 M KCl, pH 6.8 by freezing, it was found that the order of effectiveness was sorbitol ?? xylitol > sucrose ?? glucose ?? fructose > mannitol.
5. The protective effect of sugar compounds on the denaturation of actomyosin Ca²⁺-ATPase by freezing was observed to be most efficient at neutral pH. In tests conducted pH 6, 7, and 8, the order of effectiveness of sorbitol on the denaturation was pH 7>8>6.

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The acid-soluble nucleotides, nucleosides and bases were extracted from the squid liver, Ommastrephes sloani pacificus (STEENSTRUP) with cold perchloric acid. They were separated by anion exchange chromatography (Fig. 1) and paper chromatography, and identified by using ultraviolet spectra, paper chromatography and by determinations of phosphate and ribose as described previously. The compounds detected were as follows: AMP, ADP, ATP, UMP, UDP, UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine, IMP, CMP, GMP, GDP, CDP-derivative, NAD, NADP, ADP-ribose, ATP-ribose, nicotinamide mononucleotide, adenine, adenosine, uracil, uridine, hypoxanthine, inosine, xanthine, guanosine, nicotinamide and nicotinic acid. The contents of total adenine nucleotides, uracil nucleotides and pyridine nucleotides were 0.5-0.6, 0.3-0.6 and 0.1 μmoles per g of wet weight, respectively (Table 2). The UDP-N-acetylhexosamine predominate in uracil nucleotides, while UDP-hexose and UDP-uronic acid were not detected in the squid liver. The nucleotides pattern on the chromatogram was similar to that of the hepatopancreas of abalone.

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The purine compounds from the muscle of some fishes (mackerel, trout and rainbow trout) have been studied by the hydrochloric acid gradient-elution system on Amberlite IRA-400. By the same technique changes have also been followed in the nucleotide composition of rainbow trout muscle which was stored at an ambient temperature of about 0°C. From these studies it has been observed that in red lateral muscle, as compared with dorsal, two specificities are notable. The first is the difference in the total amounts of purine compounds especially those of inosinic acid (IMP). In red lateral muscle less amounts of the purine com-pounds are found than in dorsal muscle. The second is dependent upon the degree of splitting of IMP. In red lateral muscle there is a rapid splitting of IMP as time goes by while in dorsal the same phenomenon as in carp muscle (accumulation of IMP) is observed; as a re-sult, the amounts of inosine and hypoxanthine in the former increase rapidly. This may be due to the more strong activity of 5'-nucleotidase in the former.

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It is a well-known characteristic of actomyosin, the contractile muscle protein, to undergo superprecipitation at low ionic strength when a low concentration of ATP is added.
Attempts on superprecipitation to discriminate the actomyosin from the myosin, prepared from carp dorsal muscle in the laboratory, were successful while both actomyosin and myosin retained their active ATP hydrolyzing activity.
Observation of superprecipitation was made at protein concentrations of 0.8-1.0mg/ml in 0.10M KCl by the addition of ATP to a final concentration of 1mM.

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Living rainbow trouts, Salmo gairdnerii irideus, were decapitated and stored at an ambient temperature of 0°C. After various lengths of time the livers were homogenized in cold 0.6 N perchloric acid, and nucleotides, nucleosides and bases extracted were determined by anion-exchange chromatography. The details of the analytical procedures have been described previously.
Results obtained are summarized in Table 1 and Figs. 1-4. ATP and ADP de-creased rapidly with the accumulation of AMP and IMP. Since the dephosphorylation of nucleotide monophosphates is slower than deamination, AMP and IMP levels were high at the beginning, but after 6 hours both nucleotides and inosine decreased with the accumulation of hypoxanthine and xanthine. These changes are characteristic in comparison with those in the doasal and red lateral muscles which show the ac-cumulation of IMP and inosine for a long time. The level of adenosine was low throughout the experimental period. From these results, it may be postulated that the main pathway of the breakdown of purine nucleotides in the liver proceeds via AMP, IMP (adenosine), inosine, hypoxanthine to xanthine.
Nicotinamide-adenine dinucleotide was broken down to ADP-ribose and nico-tinamide. The UDP-sugars, which predominate among uracil nucleotides, disap-peared rapidly.

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(1) 放線菌No.41株の生産する酵素系を用いてイカ肉の酵素的分解を試みた結果,蛋白質が加水分解され多量のアミノ酸を生ずるとともに,イカ肉中の5'-AMPはほぼ定量的に5'-IMPに変換した.
(2) 分解液は強い旨味を呈し,かんたんな後処理を加えることにより食品用調味基材として好適なものとなった.
(3) 5'-AMPデアミナーゼの二,三の酵素的性質について検討を加えた.

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It was previously reported that the turbid protein extracts from fish muscle contained a gel fraction. In order to investigate the relationship between the gel fraction and myofibrillar protein, some properties of the former were examined. The gel fraction was prepared from frozen- or ice-stored muscles of both the flatfish, Kareius bicoloratus, and Alaska pollack, Theragra charcogramma, by extraction using KCl-phosphate buffer (I=0.5, pH 7.2) and cen-trifugal sedimentation at 30, 000-40, 000×g.
The absorption curve of the gel fraction was similar to that of actomyosin. The gel fraction did not show streaming birefringence by OKADA's apparatus. On addition of ATP to the gel fraction at low ionic strength, superprecipitation occurred forming a loose slurry-like precipitate. The viscosity of the redispersed solution (I=0.5) of the gel fraction fell sharply on addition of ATP, but the ATP sensitivity values were not very high. The gel fraction had Mg-ATPase activity at low ionic strength (0.03 M KCl). These properties of the gel fraction are similar to that of actomyosin with the exception of streaming birefringence. As a result, the author considers that the gel fraction may contain an aggregated protein which involves myofibrillar protein and that the shape of the aggregate may not be so thread-like.

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It has been believed that the tendency of fish myosin to denature is much greater than that of rabbit during repeated precipitation by dilution.
An investigation was made to purify carp myosin and actomyosin by the usual dilution method. The preparations obtained at each step of precipitation were characterized by measuring ATP-ase activity, ATP-sensitivity, and activities of other contaminating enzymes (myokinase and adenylic deaminase).
Crude myosin usually had ATP-sensitivity of 5-20. Some which had slightly higher values were improved by an intermediate precipitation at a KCl concentration of 0.28 mole/l.
The crude preparations of myosin and actomyosin usually contained myokinase and adenylic deaminase. The repeated precipitation resulted in virtually complete removal of myokinase but not of adenylic deaminase.
It was observed that specific ATP-ase activity of myosin preparations decreased slightly during repeated precipitation by dilution, while those of actomyosin preparations remained almost constant.
The above results suggest that myosin denaturates slightly during repeated precipitation by dilution.

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Guanine and hypoxanthine contained in the skin of Hime (Kokanee) salmon, Oncorhynchus nerka f. adonis, cherry salmon, Oncorhynchus masou f. mason, rainbow trout, Salmo gairdnerii irideus and brook trout, Salvelinus fontinalis were analyzed.
The purines were found several times richer in the ventral skin of the fish than in the dorsal skin (Fig. 2 and Table 3). In the stages showing silvery color, the purines appeared deposited mostly on the scale and in a white layer between the dermis and muscle, which is tentatively called “skin layer” by JOHNSTON and EALES⁵⁾ (Fig. 3 and Table 4). The purines in the skin of non-silver fish showed a tendency to decrease as the fish grew, from 8 to 32 months old. On the contrary, those in silver fish were several times, sometimes ten times higher in content than those in the non-silver fish 8 to 32 months old (Tables 5, 6 and 7).
Considering the fact that fish gains much in weight during this period, it may be concluded that the purines in silver fish are continually synthesized and deposited at this stage. However, in non-silver fish such synthesis do not seem to take place, and therefore, the deposition of purines could not be observed.

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