Alcoholic fermentation / by Arthur Harden.

  • Arthur Harden
Date:
1932
Catalogue details

Licence: In copyright

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

    150/258 page 140
    occur in the later stages. It will be noted that Meyerhof and Lohmann ascribe to the stabilised monophosphate exactly the same fermen- tation reactions as to the “ active ” form. Euler and Myrback [1928, 2] consider that in this change half the ester is decomposed and fermented and the other half esterified. Working with washed zymin and purified co-enzyme (+ a little hexose- diphosphate) they found that inorganic phosphate did not influence the fermentation, and that no change in inorganic phosphate occurred until the velocity of fermentation slackened, at which period they suppose that half the monophosphate has been fermented and the other half converted into diphosphate, which was then decomposed in the usual way. Harden and Robison’s (unpublished) experiments, made with zymin, agree with those of Meyerhof and Lohmann, but they have further observed that the ester is only fermented with enhanced velocity when free phosphate is present, so that this stage of the fermentation represents some change in which phosphate plays an active part. Thus I c.c. M hexosemonophosphate, added to zymin and water, gives a short period of enhanced fermentation, varying with the amount of inorganic phosphate present. When a further addition of hexosemonophosphate is made to this mixture no enhanced fermentation occurs, but if phosphate be then added an enhanced rate of fermentation is again set up. The proportion of ester thus fermented at an enhanced rate is always small (J-i) and is approx- imately the same for both the Neuberg and the Robison ester. Neuberg and Kobel’s [1928, 3] observations agree with those of Harden and Robison and of Meyerhof in that they show that a small proportion of the ester is fermented at a high rate comparable to that of fructose and phosphate. In view of the small proportion which undergoes this rapid reaction they regard their observations as decisive against the idea that the hexosemonophosphate, as isolated, can be regarded as a necessary intermediate product of alcoholic fermentation. What the explanation of these phenomena is remains so far un- known, but it is obvious that the course of this reaction cannot at the moment be legitimately used as evidence in favour of any one of the various systems of fermentation at present in the field. It must also be remembered that all the hexosemonophosphoric esters hitherto sub- mitted to fermentation contain at least two and sometimes three constituents.
    digitised image 1
    digitised image 2
    digitised image 3