CATALYSIS AND ENZYMES 



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see a photograph of the laboratory in which he worked from 1877 to 1887, a 

 period of time in which so much of fundamental importance was produced The 

 photograph of van't Hoff's workroom, reproduced in Fig. 85, and that of the 

 exterior of the laboratory in Fig. 86 are taken from the book by Jorrisen and 

 Reicher (1912). Fig. 87 is an interesting picture of Ostwald and van't Hoff. 



We have already had occasion to refer to some facts concerning the 

 reversibility of enzyme action. We saw that the equilibrium point may be 

 in very various positions according to the relative rate, as determined by 

 the chemical difficulty, of the two opposing reactions. We have seen how, at 

 this equilibrium point, the two opposing reactions are to be regarded as still pro- 



FIG. 87. VAN'T HOFF AND OSTWALD IN OSTWALD'S LABORATORY AT LEIPZIG. 



(Reproduced by the kindness of Prof. Ernst Cohen 

 of the van't Hoff Laboratory, Utrecht.) 



ceeding, but at equal rates. The reaction with the slower natural rate is 

 compensated for by the greater active mass at the state of equilibrium. It is 

 to be remembered that the actual position of equilibrium is decided by the 

 relative values of the two velocity constants. The ratio of these constants is 

 obviously also a constant and is known as the equilibrium constant. We note 

 further that the equilibrium position can be defined in two ways, either from 

 the dynamical point of view, as above, by the ratio of the two velocity constants, 

 or, from the statical point of view, as the ratio of the relative masses of the com- 

 ponents. It is interesting to find that the equilibrium constant in the lipase 

 reaction of Dietz, given at the commencement of this chapter, is found experi- 

 mentally to be the same when calculated in both ways. 



Although the equilibrium position can be defined by the relative masses of 



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