Abstract
A crystalline substance melting sharply at 223° C. has been isolated by the use of differential adsorbents from autolyzed yeast which in very small amounts (0.005 mg. per cc. of Fulmer's medium F.) produces during a 24 hour incubation at 31° C. a volume of yeast growth fifteen to twenty times that in the controls.
Microphotographs made with the petrographic microscope were exhibited to demonstrate the homogeneity of the crystalline product together with evidence obtained by recrystallizing the product first from water and then twice from alcohol.
The recrystallized product retains its constant melting point and shows no loss of activity.
Curves based on yeast tests made with varying concentrations of autolyzed yeast and of the crystals were shown to demonstrate that the form of curve is identical in the two instances, both showing an optimum concentration and lesser stimulation for concentrations on either side of the optimum concentration.
The yield of the product was about 0.03 per cent of the dry weight of the autolyzed brewer's yeast used. The carbon and hydrogen percentages have been determined and are : Carbon, 43.29 per cent; hydrogen, 8.31 per cent. The nitrogen content has not yet been accurately determined but will apparently run in the neighborhood of 25 per cent. The substance gives no ninhydrin or biuret reaction. It is freely soluble in cold water, in acid and alkaline solutions and in dilute ethyl alcohol. In cold 95 per cent alcohol it is sparingly soluble but passes readily into solution when the alcohol is heated. It is only slightly soluble in 100 per cent acetone but very slight dilution of the acetone with water brings about its solution.
The essential feature of the method of isolation consists in a preliminary purification of autolyzed brewer's yeast with fullers earth which removes other substances than bios, and then the use of ferric hydroxide in colloidal sol which under specific conditions devised by Dr. Kerr removes the bios and can later be dissolved and the bios freed from cantaminating ions.
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