300 SCIENCE PROGRESS 



affect the action of invertase, whereas fructose has a consider- 

 able action of this kind. If an enzyme accelerates the reverse 

 reaction, as well as the usual hydrolysis or splitting-up, it is 

 easy to understand why it is capable of combining with 

 products of reaction in addition to combining with the unaltered 

 substrate ; if we suppose that in order to exert its catalytic 

 influence it must enter into some such intimate connection with 

 the bodies to be acted upon, such "compounds" must be formed 

 between enzyme and products before synthesis of the latter will 

 occur. 



Enzymes, being colloids, are particularly prone to form 

 adsorption compounds, so that we naturally look for evidence 

 as to the nature of the compounds in question. The fact that, at 

 all events in the logarithmic stage of the reaction, increasing the 

 concentration of the enzyme to say twice its value does not 

 double the reaction velocity, but something less than this, is 

 considerable evidence in this direction. A relationship of this 

 nature is characteristic of adsorption phenomena. It also tends 

 to confirm the view of Victor Henri that the enzyme is shared 

 by the substrate and the water present in such a manner that 

 the proportion taken up by the former is greater the lower the 

 concentration of the enzyme. If we put : a = the quantity of 

 enzyme adsorbed from a solution of concentration = i, and b — 

 that adsorbed from a similar solution of concentration = 2, then 

 a = b x 2~f, in which x is what is called the " proportionality 

 factor," and is always greater than unity, which value it would 

 have if the process were a purely physical one, such as solid 

 solution, for example. The higher the value of x the more 

 nearly the process approximates to a chemical combination, 

 in which case it is obvious that a = b, and therefore 2^ in the 

 above expression becomes unity or x = infinity. In the case 

 of trypsin x varies from 1*5 to i'6y, and according to Schutz 

 and Borissow's " law of squares " — which is, however, merely a 

 special case — x =2. I find in some experiments made recently 

 that in the case of Congo-red and paper x is usually less than 2, 

 about 1 '6 in fact, but it varies considerably according to the 

 amount of electrolyte present. It would appear, then, that the 

 union of enzyme and substrate follows a similar law to that of 

 ordinary adsorption phenomena. 



A particularly interesting case as regards the question before 

 us is that of the lipase of the liver as investigated by Dakin. 



