Changes induced by E-avitaminosis on the proteins of rabbit-muscle extracts

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Abstract
A muscle extract made at high ionic strength obtained from E-avitaminotic rabbits was divided into 3 fractions corresponding (a) to actomyosin, (b) to myosin, and (c) to the proteins salted-out from the supernatant at 48% ammonium sulfate saturation. Total extractable proteins are decreased in dystrophy and the proportions of the 3 fractions are also changed. The 1st fraction, which is normally precipitated as actomyosin by the splitting of adenosine triphosphate, has mainly the physiochemical properties of myosin in subdystrophic animals, whereas in fully dystrophic rabbits the viscosity and KCl-solubility properties are those of actomyosin. Salting-out and electrophoretic patterns show a marked decrease of myosin content, and an unknown component appears which has a slower electrophoretic mobility and precipitates at lower ammonium sulfate saturation. The 2d fraction still retains its myosin properties in subdystrophic rabbits, but in advanced dystrophy several changes take place: a decrease in viscosity, in KCl -solubility and in adenosine triphosphatase activity. These effects are to be correlated with the disappearance of myosin as shown by salting-out and electrophoretic experiments; the latter indicates also that in this fraction the unknown component which is precipitated at 12-14% saturation with ammonium sulfate predominates and has a very low electrophoretic mobility. Under normal conditions the 3 fraction contains, amongst other components, tropomyosin and Y-protein, but in dystrophic rabbits these proteins have a strong tendency to unite in rather stable complexes which probably include tropomyosin. Fractions I and H show a high content of ribonucleic acid, in advanced dystrophy.