62 ENZYMES 



substantiated the belief of their existence that had become 

 general before it was thus finally corroborated. Growing out 

 from this and subsequent experiments has come a larger and 

 larger amount of evidence that many of the chemical activities 

 of the cells are due to the enzymes they contain, until now the 

 point is reached where one may rightfully ask if cell life is not 

 entirely a matter of enzyme activity. There are certain facts, 

 however, which seem to indicate that there are some essential 

 differences between cells and enzymes. One of the most 

 important of these is the difference in the susceptibility to poi- 

 sons of enzymes and cells. Strengths of antiseptics that will 

 either destroy or inhibit the action of living cells, such as alco- 

 hol, ether, salicylic acid, thymol, chloroform, tuluol, and sodium 

 flouride, will harm free enzymes in solution little or not at all. 

 This fact has been of great assistance in distinguishing between 

 the action of enzymes and of possible contaminating bacteria in 

 experimental work. Although this difference between enzymes 

 and cells is characteristic, it does not finally decide that the cell 

 actions are not enzyme actions, for it may well be that the poi- 

 sons act chiefly by altering the physical conditions of the cell 

 so that diffusion is interfered with, thus seriously interfering 

 with the exchange of splitting products between different parts 

 of the cell, and checking intracellular enzyme action, which we 

 shall see later requires free diffusion of the products for its con- 

 tinuance. 1 At the very least, however, we may look upon the 

 intracellular enzymes as the most important known agents of 

 cell metabolism, and consequently of all life manifestations,^ 

 and the changes they undergo or produce in pathological condi- 

 tions must be fully as fundamentally important as is their rela- 

 tion to physiological processes. It therefore becomes necessary 

 for us to consider carefully 



THE NATURE OF ENZYMES AND THEIR ACTIONS 2 



Since up to the present time no ferment has been isolated in 

 an absolutely pure condition we are entirely unfamiliar with 



1 Kaufman points out another important defect in the experiments indicating 

 a difference between the effects of poisons on enzymes and on cells, namely, that 

 in the experiments the concentration of enzymes is high, whereas in most cells- 

 it is low. Solutions of trypsin stronger than 0.2 per cent, are not much 

 affected by toluol, thymol, etc., during twenty-four hours, but weaker solu- 

 tions are those less than 0.02 per cent, being rendered inert. (Zeitschr. 

 f. physiol. Chem., 1903 (39), 434.) 



2 It would not be profitable to discuss fully all the various theories and hypoth- 

 eses that have been advanced, but the reader is referred to the following 

 chief compilations of the entire subject : Oppenheimer, " Die Fermente und 

 ihre Wirkungen," Leipzig, 1903, Effront, " Enzymes and their Applications," 



