GENERAL CHEMISTRY OF LIFE PHENOMENA \ r 



Neilson* has shown that the catalytic action of lipase on ethylbuty- 

 rate can be imitated by platinum-black. The latter not only acceler- 

 ates the hydrolysis, but also the synthesis of ethylbutyrate. Kastle 

 and Loevenhart found that certain poisons like hydrocyanic or sali- 

 cylic acid weaken the action of lipase. Neilson found that these poisons 

 act similarly on the digestion of ethylbutyrate by platinum-black. 



The study of the reversible action of enzymes in the carbohydrate 

 group is complicated by the fact that the digestion of starch to sugar 

 occurs in a series of successive stages, and that apparently each stage 

 requires a different catalyzer. According to Duclaux,f we possess 

 specific enzymes for the transformation of solid into liquid starch ; the 

 liquid starch is then split by amylase or diastase into a disaccharide, 

 i.e. maltose. Maltose is split by the enzyme maltase into d-glucose. 

 In case another disaccharide is formed in the place of maltose, other 

 enzymes are required, e.g. in the case of cane sugar, invertase, whereby 

 dextrose and laevulose are formed. In the animal body, glycogen is 

 formed in the place of starch. It is obvious that the synthesis of dex- 

 trose into glycogen or starch requires the presence of several catalyzers. 

 The action of these catalyzers must be studied individually. 



Hillij: found that the hydrolysis of maltose in the presence of the 

 enzyme maltase is retarded if dextrose is added to the maltose; that, 

 moreover, the hydrolysis of maltose under the influence of maltase is 

 complete only in very dilute solutions, while the reaction otherwise 

 comes to a standstill before all the maltose is transformed into glucose. 

 The following table shows the point at which the hydrolysis comes to 

 a standstill at various concentrations: 



,. PERCENTAGE OF MALTOSE WHICH 



CONCENTRATION OF MALTOSE , s spUT , NTO GLUCOSE 



40% 84% 



10% 94-5% 



4% 98% 



2 % 99% 



Hill convinced himself that if the enzyme maltase is added to a solu- 

 tion of glucose, maltose is formed, and that, moreover, equilibrium 

 is reached at the same point as in the case of hydrolysis. When he 

 added fresh maltase to a 40 per cent solution of dextrose in one 

 experiment, 14.5 per cent, and in another 15.5 per cent, maltose 

 was formed. It has since been shown that the synthetical product 

 formed in this case was isomaltose instead of maltose, but this slight 

 deviation does not alter the principal result. 



* Neilson, Am. Jour. Physiology, Vol. IO, p. 191, 1903. 

 t Duclaux, Traite de microbiologie, Vol. 2, Paris, 1899. 

 } A. C. H\\\,Joitr. Chem. Society, Vol. 73, p. 634, 1898. 



