CATALYSIS AND ENZYME ACTION 69 



centimetre radius has a surface of 0*126 sq. cm., while the 

 surface of the same mass, if subdivided to the above colloidal 

 dimensions, would have a surface of about 100 sq. m., or be 

 multiplied by ten millions." * 



At present we cannot definitely decide between the above 

 hypotheses. The specific relation of the enzyme to the 

 substrate and the specific inhibiting effect of some of the 

 products of reaction seem to point to the formation of 

 intermediate compounds. On the other hand, it is said that 

 " specific adsorption " can occur, but the nature of this 

 " specific adsorption " is difficult to understand. Electrical 

 effects can act only when the particles are positively or 

 negatively charged. Possibly the " specific adsorption " is 

 a link between the purely physical adsorption and chemical 

 combination as specific relations are more in the nature of 

 chemical reactions. 



The two views may be united by saying that the adsorption 

 brings the substances together, and then some loose chemical 

 union occurs which breaks down with the formation of the 

 products of reaction. 



DIRECTIVE ACTION OF ENZYMES 



In many cases a chemical substance may be altered by 

 several different paths giving rise to different end products. 

 In organic synthesis the methods chosen are those which give 

 the greatest yield of the desired product. The acceleration 

 of one reaction will produce a greater yield of the product 

 formed by that reaction, hence enzymes are useful for the 

 formation and isolation of some substances. 



CO-ENZYMES 



Enzymes are sometimes said to be composed of two 

 substances, enzyme and co-enzyme. Hydrochloric acid is 

 stated to be the co-enzyme for pepsin. The discussion on 

 p. 63, in which the possibility is pointed out that alkali 

 increases the action of trypsin by producing an active ion, is 

 applicable to the case of hydrochloric acid and pepsin. 



Lipase, or fat splitting enzyme, is composed of two parts, 

 one soluble in water and passing through filter paper, the 

 other removed by filtration. Both are present in the crude 

 extract obtained by treating an organ with glycerine. f 



* W. M. Bayliss, The Principles of General Physiology. Longmans, 

 Green & Co., 1915, p. 79. 



f O. Rosenheim, Journ. Physiol., 1910, vol. 40, Proceedings, p. 14. 



