90 



Dr. W. M. Bayliss. 



[Apr. 7, 



The Law Connecting Concentration and Activity of Enzymes. 



If the velocity of enzyme action is conditioned in any given case by the 

 amount of adsorption which has taken place, it follows that when the 

 relative concentration of enzyme and substrate is varied, the corresponding 

 change in the rate of action will be an exponential function of the concen- 

 tration. If, for example, the concentration of the enzyme is doubled, the 

 velocity of the reaction will not thereby be doubled; if the velocity with 

 concentration of enzyme = 1 be called a, that with enzyme concentration 

 = 2 will not be a x 2, but an expression of the form a x 2 l l n will be 

 required, where n is, as a rule, any number between 1 and 2. 



It is not the purpose of the present paper to find a general law which 

 shall apply to all enzymes under all conditions. The experiments to which I 

 intend to refer were made in order to see whether it is necessary to make 

 use of an exponential form of expression, in which it may be regarded as 

 probable that the value of the exponent will vary from case to case. If this 

 is so, we may reasonably conclude that an adsorption process is the controlling 

 factor. 



In all experiments whose object it is to compare the action of the same 

 enzyme in varying concentrations, it is imperatively necessary that the times 

 taken by each respectively to produce the same amount of change be taken 

 as the basis of comparison. It is very usual to find that, during the course 

 of a reaction progressing under the action of an enzyme, substances are 

 formed which act either as accelerators or retarders as the case may be. A 

 species of autocatalysis, positive or negative, takes place. For example, 

 trypsin acts most rapidly in alkaline solution, but in the process of hydrolysis 

 of proteins by its agency, amino-acids are produced which neutralise a larger 

 and larger part of the alkali as the reaction goes on. On this account it is 

 inadmissible in accurate work to take as basis of comparison the different 

 amounts of change produced in equal times ; the reaction is not at the same 

 stage in both, so that the concentration of accelerator or retarder is different. 

 If the object is merely to detect whether one of the two solutions is stronger 

 than the other, of course the change in equal times may be compared. 



My experiments have been made with trypsin and with invertase. 



The trypsin experiments were done in the following way : A number of 

 small stoppered flasks fitted with electrodes for the purpose of measuring 

 the electrical conductivity of the contents were supplied each with 10 c.c. of 

 5-per-cent. ammonium caseinogenate. When warmed in the thermostat at 

 39° C, 2 c.c. of trypsin solution in the various dilutions required were added 

 in turn to each and the electrical conductivity determined at intervals. 



