86 



Dr. W. M. Bayliss. 



[Apr. 7, 



2. The Part Played by Adsorption in Enzyme Action. 

 In a paper published some five years ago,* I suggested the view that an 

 adsorption compound is formed between an enzyme and its substrate 

 preliminary to the chemical reaction properly so-called. That combination 

 of some kind occurs is generally accepted, so that my hypothesis is to be 

 regarded as a more definite statement as to the nature of this compound. 

 It does not, indeed, exclude a subsequent combination of a more truly 

 chemical nature. 



The evidence in favour of the adsorption hypothesis is mainly indirect, 

 but during the time succeeding its first publication numerous facts have 

 come to light which confirm it in a variety of ways. Some of these facts 

 which have been the subject of investigation by myself will be discussed in 

 the present paper. 



Two main lines of experiment have been pursued. In the first place, the 

 process by which enzymes are removed from their solutions by substrate 

 or inert bodies, such as charcoal or paper, will be briefly considered, and in 

 the second place, the significance of the form of the mathematical expression 

 correlating the concentration of the enzyme with the degree of activity will 

 be shown. 



Adsorption of Enzymes by Surfaces. — The work of many investigators has 

 proved that many various substances, with which it is difficult to suppose 

 that enzymes are capable of forming chemical compounds, are able to 

 remove them from solution. Such bodies are charcoal, kaolin, sand, and 

 paper. When, therefore, we find that enzymes are removed by colloidal 

 substrates, the hypothesis naturally suggests itself that a similar process 

 takes place, surface concentration will occur whether the adsorbed body can 

 act further or not. I showedf that calcium caseinogenate is capable of 

 removing from solution, in some form or other, both trypsin and diastase. 

 Now although it is possible that there may be chemical combination in the 

 case of trypsin and caseinogen, since chemical decomposition results from 

 the contact, it does not seem likely that a similar state of affairs obtains 

 in the case of diastase and caseinogen, a substrate upon which the enzyme 

 has no action. By analogy with certain other catalytic phenomena, it seems 

 reasonable to hold that, when chemical action results, an intermediate 

 compound of a chemical nature has been formed, subsequent to adsorption, 

 and that this compound afterwards breaks up, setting free the enzyme at the 

 same time as the products of its activity. 



* ' Biochem. Joum.,' 1906, vol. 1, pp. 222—226. 

 t ' Biochem. Journ.,' 1906, vol. 1, p. 224. 



