Alcoholic fermentation / by Arthur Harden.

  • Arthur Harden
Date:
1932
Catalogue details

Licence: In copyright

Credit: Alcoholic fermentation / by Arthur Harden. Source: Wellcome Collection.

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    water, and (b) in presence of much monophosphate some of this is carried down (probably as a double salt) along with the hexosedi- phosphate. Preparation of Barium Hexosediphosphate.—The diphosphate can readily be obtained pure [Robison and Morgan, 1930] by extracting the precipitate obtained with barium acetate and baryta with 200 parts of water at pR 8*6 at 0°. The clear liquid, which should be free from inorganic phosphate, is treated with alcohol until a slight cloud forms and is then heated in 200 c.c. portions to 70° in a water-bath and filtered hot. The diphosphate remaining in solution can be recovered in a somewhat less pure condition by adding more alcohol and again heating at J0°. Purification by means of precipitation by lead acetate and decomposition of the washed precipitate with H2S, the method originally used by Young [1909], is of little advantage and often leads to hydrolysis during the decomposition by sulphuretted hydrogen. Barium hexosediphosphate should be dried at low temperatures, otherwise hydrolysis may occur. Other less satisfactory methods of preparation have been described by Lebedev [1910] and Euler and Fodor [1911]. Salts of hexose- diphosphoric acid are manufactured by Messrs. Bayer, the calcium salt being known as candiolin. Preparation of the Hexosemonophosphates.—The treatment of the filtrate from the sparingly soluble precipitate obtained in the prepara- tion of the hexosediphosphate varies according to the nature of the yeast preparation used and the hexosemonophosphate sought for. Trehalosemonophosphoric Ester [Robison and Morgan, 1928, 2] (Fermentation carried out with dried yeast).—One-tenth of its volume of alcohol is added to the filtrate from the sparingly soluble barium salts and any precipitate which forms is filtered off. This consists largely of hexosediphosphate. To the filtrate a slight excess of basic lead acetate is added and the precipitate washed and decomposed by H2S. The filtrate from the PbS is freed from H2S by aeration, brought to pK 8*4 with baryta and poured into two volumes of alcohol, the precipitated barium salts being washed with alcohol and rapidly dried in vacuo. The dried precipitate is then ground with 10 parts of water, a volume of alcohol equal to one-tenth of the volume of the water is added, the residue (which may contain some hexosediphosphate, hexosemonophosphate, and trehalosemonophosphate) is filtered off, washed and dried, and the filtrate poured into two volumes of alcohol. This final soluble fraction consists of varying proportions of hexose- and trehalosemonophosphate, and may still contain a small
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