96 



Dr. W. M. Bayliss. 



[Apr. 7, 



protects an enzyme from the destructive action of a raised temperature 

 indicates chemical combination between the two bodies. It seemed, 

 therefore, of interest to see whether an indifferent substance like charcoal 

 would also protect enzymes by adsorbing them. In order to make the 

 conditions equal in comparing the activity of a preparation which had been 

 heated in presence of charcoal with that which had been heated alone, 

 charcoal in the same amount was added to the latter after heating and when 

 caseinogen was added to both. It is necessary to remember that, as Hedin 

 has suggested,* when the adsorption compound of trypsin with charcoal is 

 brought into caseinogen solution, the latter body may remove the enzyme 

 from the charcoal by its greater adsorption " affinity." The first experiment, 

 in which the enzyme was heated only to 47° for an hour, showed little loss 

 of activity, and to the same extent both with and without charcoal. Another 

 experiment, in which the solutions were heated to 60° for 10 minutes, 

 showed that charcoal had protected the enzyme to a certain degree. The 

 activity of the enzyme heated in presence of charcoal was such as to cause a 

 change of 1440 recip. megohms in two and a quarter hours, as against one of 

 1270 recip. megohms in the case of the enzyme heated alone. 



Simple adsorption, therefore, exercises a protecting influence, and it is 

 unnecessary to postulate chemical combination in order to explain the 

 protective action of substrate or products. 



The fact that there is an exponential relation between the concentration 

 of an enzyme and the degree of its activity suggests that some kind of an 

 adsorption process intervenes as a factor in the rate of the reaction. To 

 obtain an equation for trypsin in which the value of the exponent is 

 constant would be a matter of much difficulty, since the adsorbing surface 

 is continuously changing as the chemical reactions split up the colloidal 

 substrate to amino-acids, etc. Moreover, as recent work by G. C. Schmidtf 

 has shown, the simple adsorption equation given on a previous page applies 

 only to a particular and somewhat narrow range of concentration in various 

 adsorption processes. In order to include wide differences, a more complex 

 formula is required. Tor our purpose, it is sufficient to bear in mind that 

 an apparently linear relationship in the initial part of a reaction, or with 

 very low concentration of adsorbent, does not preclude adsorption. Again, 

 Denham has] pointed outf that the results of Frankland Armstrong§ on 

 lactase, in which there seems to be a different law correlating concentration 



* ' Biochem. Journ.,' 1906, vol. 1, p. 481. 

 t ' Zeitsch. f. physik. Chem.,' 1910, vol. 74, p. 689. 

 + ' Zeitsch. f. physik. Chem.,' 1910, vol. 72, p. 690. 

 § ' Eoy. Soc. Proc.,' 1904, vol. 73, p. 508. 



