Alcoholic fermentation / by Arthur Harden.

  • Arthur Harden
Date:
1932
Catalogue details

Licence: In copyright

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

    73/258 page 63
    salt is slowly fermented by living yeast, differing in this respect from that of the hexosediphosphoric acid [Neuberg, 1918, 2]. This sub- stance is also fermented by yeast-juice and zymin. The Ba salt has [a]D + 0-4° and the free acid + 1*5°. Its dissociation constants are the same as those of the Robison ester (p. 54). It has approximately the same reducing power to Bertrand’s or Hagedorn and Jensen’s reagent as the fermentation ester (78 per cent.), but its behaviour to hypoiodite (about 5-10 per cent.) indicates that it consists almost exclusively (90-95 per cent.) of a keto-ester, but appears to contain about 5-10 per cent, of an aldo-ester. The keto- component may possibly be fructo-furanose-6-phosphoric acid, the readily hydrolysable phosphoric group in position I of hexosedi- phosphoric acid (p. 59) having been removed. The salts of Pb, Ba, Ca, Mg, and Mn are readily soluble in water and those of strychnine, brucine, and cinchonidine are crystalline [Neuberg and Dalmer, 1922]. A remarkable property of this ester is the ease with which it under- goes oxidation at pn 8 in presence of a trace of copper. Under these circumstances in a phosphate buffer the Neuberg ester absorbs oxygen twice as quickly as fructose, and about five times as rapidly as the Robison monophosphoric ester. The figures given by Meyerhof and Lohmann [1927] are as follows for 0-033 M solutions in M phos- phate or arsenate of pK 8 at 370 in 1-5 hours. Fructose ..... mm3 02 Absorbed. 37'i Oxidation Velocity. IOO Glucose ..... 5-3 14 Neuberg ester : (hexosemonophosphoric ester) 8o-6 220 Robison ester : (hexosemonophosphoric ester) 16-9 46 Hexosediphosphoric ester . 1*0 O This is held by Meyerhof to indicate that in the Neuberg ester the hexose residue is in a condition of peculiar instability, and thus supports his thesis that this substance is intimately concerned in the early stages of fermentation (see p. 136). The oxidation of fructose in presence of phosphate appears not to proceed by way of the inter- mediate formation of a hexosephosphate [Neuberg and Kobel, 1925] Trehalosemonophosphoric Ester. The barium salt of this ester appears to exist in two forms, one amorphous and readily soluble in water, the other crystalline, con- taining 5H20, and sparingly soluble in water. It has no reducing
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