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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    of the reducing power to the rotation of the product of hydrolysis is greater than corresponds with pure fructose is explained by Neuberg as due to the formation of a reducing by-product of low rotation, a similar effect being produced when synthetic fructosemonophosphoric acid is hydrolysed [Neuberg and Kretschmer, 1911 ]. The hexosemonophosphate obtained by partial hydrolysis of the diphosphate with acid (Neuberg), even when prepared from a carefully purified specimen, reacts to a small extent with iodine, the amount of aldose thus indicated being about 7 per cent. [Robison and King, 1931]. The reducing power towards Bertrand’s solution is about 42 per cent. [Meyerhof, 1930, p. 74], and to Hagedorn and Jensen’s reagent [Robison and Morgan, 1930] 40 per cent, of that of the equivalent amount of glucose in presence of 0*5 M sodium hydroxide. The acid itself only reduces Fehling’s solution after some hours in the cold, rapidly when boiled, whereas when its solution is first boiled, and then treated with Fehling’s solution in the cold, the products of decomposition bring about reduction in a few minutes. With sodium hypoiodite (which oxidises aldoses but not ketoses) hexosediphosphate gives only a slight reaction, according to Meyerhof equal to about 4 per cent, of that of the hexose present (whilst fructose itself gives 2-5 per cent). This indicates that the hexose residue is almost exclusively a ketose. On the other hand, when the phosphate groups are removed by the hydro- lytic action of bone phosphatase the sugar obtained (like that obtained by Young by acid hydrolysis) is considerably less laevo-rotatory than fructose [Martland and Robison, 1929]. The same enzyme on the other hand liberates pure trehalose from trehalosemonophosphoric ester. This affords an instance of the complicated and little understood nature of the changes which the sugar residues of these phosphoric esters undergo. (See also p. 68.) The behaviour of the compound towards phenylhydrazine is also in complete agreement with this view. Lebedev found [1909, 1910] that the acid or its salts heated with phenylhydrazine in presence of acetic acid gave an insoluble compound, which was ultimately found to be the phenylhydrazine salt of hexosenionopliosphoric acid osazone C6H6NH • nh2 • h2po4 • C4H5(OH)3 • C(N2HC6H5)CH(N2HC6H6) [Lebedev, 1910 ; 1911,5; Young, 1911 ]. After recrystallisation from alcohol this compound forms yellow needles, melting at 1510 to 1520. It is decomposed by caustic soda yielding a sodium salt Na2P04 • C4H6(OH)3 . (CN2HC6H6) • CH(N2HC6H6)
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