Alcoholic Fermentation. 



45 



involved, it was found impossible to obtain any clear insight into 

 the conditions of physico-chemical equilibrium obtained in this 

 reaction. Buchner's dauerhefe, that is to say, a preparation of 

 pressed yeast precipitated by an excess of acetone or alcohol 

 ether, can be prepared in large quantities and exhibits a high 

 degree of resistance to the action of destructive enzymes. We 

 therefore directed our attention to the preparation of dauerhefe 

 containing as large a zymase content and as small a co-enzyme 

 content as possible, our object being to study the effect exerted 

 by a preparation of this nature upon fermentable sugars, when 

 used in conjunction with varying proportions of a boiled yeast 

 extract containing co-enzyme. It was found possible to produce 

 a preparation of acetone dauerhefe which in itself alone possessed 

 no fermentative activity whatsoever, but which when used in con- 

 junction with a suitable quantity of boiled yeast extract, exhibited 

 an unusually active fermentation, 2 grams mixed with 6 grams of 

 sugar and 20 c.c. of extract producing from i to 2 grams of COj 

 in the course of 8 to 10 days. 



Having thus demonstrated that it is possible to obtain a stable 

 preparation containing relatively large quantities of zymase, and 

 also to prepare a relatively stable boiled extract of yeast contain- 

 ing co-enzyme, a series of experiments was commenced, the object 

 of which was to determine the effect of varying proportions of 

 co-enzyme used in conjunction with a constant amount of zymase, 

 and vice versa. In several series of experiments in which a con- 

 stant amount of zymase (2 grams dauerhefe^, was used in con- 

 junction with 6 grams of sugar and from i to 50 units of co- 

 enzyme, it was found that the velocities of reaction and the 

 fermentation end results were directly proportional to the number 

 of units of co-enzyme employed up to an optimum concentration, 

 after which a fall in the value of both these quantities was to be 

 observed. The same phenomenon exhibited itself when varying 

 proportions of dauerhefe were employed with a constant amount 

 of co-enzyme, other conditions being constant. 



The velocity of reaction k, is calculated from the formula 



