Salting-out Behavior Research Articles

Studies on the denaturation of fish muscle proteins. I. Physico-chemical and electron microscopical studies of freeze-denatured carp actomyosin.

With a view to exploring the molecular nature of the freeze-denaturation of muscle proteins, a multi-aspect study was done on carp actomyosin including measurements of solubility, viscosity, ATP-response, salting-out behavior, ultracentrifugal behavior and electron-microscopical observations. The solubility and intrinsic viscosity of actomyosin decreased with the length of frozen storage and the ultracentrifugal patterns showed aggregation proceeding during frozen storage. However, the loss of ATP-response appearing early in frozen storage suggested the occurrence of either dissociation into actin and myosin or the loss of dissociating capacity on addition of ATP. Electron microscopical observations showed that, by freezing and frozen storage, actomyosin filaments are not only aggregated side-to-side and/or cross-wise but are entangled into net-like masses, which appear even in centrifuged supernatants after prolonged frozen storage. Salting-out analysis showed that combination of actin and myosin is generally preserved after frozen storage. It was proposed that during frozen storage, actomyosin filaments form net-worked masses through aggregation and entangling and become increasingly insoluble with the growth in net-work and particle size of the masses.

Normal peroxidase activity in Pendred's syndrome.

A 12-year-old euthyroid girl with a goiter and bilateral nerve deafness had a 29% discharge of radioiodide after perchlorate. Both parents and five siblings were euthyroid with goiter and nerve deafness, and all but the father had a positive perchlorate discharge of radioiodide. Thyroid tissue obtained during subtotal thyroidectomy contained ample peroxidase activity as measured by I3– formation and 131I incorporation into tyrosine, both of which were stimulated by the addition of hematin. There was a low iodine content in the gland which probably accounted for an increase in MIT/DIT ratio and decrease in the amount of radioiodine found in the iodothyronines, after it had been labelled in vivo with 125I. The thyroglobulin appeared to be normal by its saltingout behavior, chromatography on Sephadex G-200 and immunodiffusion. The findings suggest that the defect in the iodinating mechanism in Pendred's syndrome is a deficiency other than peroxidase activity.

The salting-out behavior of amides and its relation to the denaturation of proteins by salts.

The salting-out behavior of amides and its relation to the denaturation of proteins by salts.

水産動物肉に関する研究-XXXI

Salting-out behavior of short-time extract of fish myosins were examined of 13 kinds of fish. Sample fish meat were chopped, being passed through a chopper plate of 3mm. mesh, and extracted with 25 volumes of 0.6M NaCl (ultimate pH 6.8) for exactly 30minutes. From the pattern of the salting-out curves (Fig. 1.) these fishes used in the present study were approximately classified into the following two groups. The one was a group of fish mainly with white unfragile fleshed fishes, such as file-fish, devil stinger, bream, etc. In the salting-out curves of these species a dominant peak presumes to be myosin was always found, Another group included most of dark fragile fleshed fishes, such as fat minnow, true mullet, Japanese argentin, etc. In the latter group of fish, the myosin peak was not present or far lower than the peak of presumable actomyosin. When a sample flesh deteriorates, myosin was found to decrease, while actomyosin increase. This change was found to be more stable on the former group of fishes than the latter one.

致死条件が魚肉蛋白におよぼす影響-II

Effect of freezing and cold storage upon the extractability and salting-out behavior of muscle protein was examined, using carp killed in two different ways; one was instantly put to death by beheading and the other was beheaded after allowed to struggle in air for several hours. Fillets taken from these two groups of carp were frozen at -15°C and stored at this temperature for a period varying from 2 to 14 days. Before freezing and at each different time of cold storage, myosins were extracted from these fillets with 0.6M KCI (pH 6.6), precipitated by dilution. and the amount was measured. With isolated myosins salting-out behavior toward ammonium sulfate was determined at pH 6.9 and at the temperature of 0°C. Extractability Myosins were always extracted greater in amount from death-after-struggle group than from instant death group throughout the period of the present experiment. No significant difference, however, in the ratio of amount of myosins (M) to salt extractable protein (L), was noticed between the two groups. After frozen storage of 10 days, a slight diminution in the values of L and M was observed in the muscle of instantly killed fish, but it was not appreciable for death-after-struggle group within the limited duration of the present test. Meanwhile, the ratio M : L seemed to decrease somewhat in both groups on prolonged storage (Table 1). Salting-out Curves Around the range of 30-40% (v/v) saturation of ammonium sulfate in the salting-out curves for either group, there was found a dominant peak, which presumably pepresented myosin and actomyosin. With fresh fillet before freezing, this peak was more prominent for the instant death group than for the other. However, by freezing and subsequent frozen storage, the pattern of the curves for instant death group turned out close to those of unfrozen fillet of death-after-struggle group, and inversely the pattern of the latter group became kin to those of the former group that was not frozen. This will be obviously perceived from the mode of slope and fall in the s-c curves in the range of 30-40% saturation of ammonium sulfate (Figs. 1 and 2). In another series of experiments similarly conducted for isolated myosin gel, the results given were not quite the same as obtained for the fillets. The salting-out curve of the gel from fish killed after struggle became analogous to that of fresh, unfrozen gel from instant death group, just as seen in the case of the fillets. But the curves of frozen myosin gel from instant death group was not altered by freezing process and cold storage (compare Figs. 1. 2 and Figs. 3 and 4). It is notable in Figs. 1-4 that there was found concentration range of ammonium sulfate in which components salted-out decreased in amount with increasing concentration as the result of freezing and subsequent storage. This means that a part of components which were saltedout at concentration c1 remained in solution in the range of higher concentrations between c1 and c2. This effect will be valid for either fillet or isolated myosins gel. Actin fraction in the salting-out pattern In the previous paper ??, it was shown with fresh fillets that actin fraction appeared in the salting-out pattern of myosin fraction from carp killed after struggle, but the corresponding fraction was absent in the case of carp put to an instant death. In addition, it was mentioned that this actin fraction would not appear, if the extraction of myosins from carp killed after struggle was carried out in the presence of ATP. In the present work, it was found that when the fillets were frozen and kept for 2 days or 6 days, a prominent peak presumed as actin fraction, appeared also in the case of carp put to an instant death.