80 BACTERIAL METABOLISM ENZYMES 



the first case of reversible action that was studied. Craft Hill 

 found that the addition of maltase to a very concentrated solution 

 of dextrose resulted in the formation of a disaccharid. This he at 

 first thought was a simple reversion of dextrose into maltose, but 

 later work showed that the sugar formed was an isomer of maltose. 

 The essential fact, however, remained that the one enzyme possessed 

 both synthetic and analytic properties. 



Emulsion is an enzyme which possesses the power of decompos- 

 ing mandelic-nitrile-glucose into glucose, benzaldehyde, and hydro- 

 cyanic acid. The mandelic-nitrile-glucose is obtained by the action 

 of maltase upon the glucoside amygdalin. The total change 

 brought about by the two ferments is indicated by the following 

 equation: 



C 2 oH 2 7NOn + 2H 2 = C 6 H 8 CHO + HCN + 

 Amygdalin. Benzaldehyde. Hydrogen cyanid. Glucose. 



Lipases act upon the neutral fats and are widely distributed in 

 both plant and animal cells. They bring about a reaction which 

 may be expressed by the following general reaction, where R = 

 the residue of a fatty acid. 



GHz R CH 2 OH 



I I 



CH R + 3H 2 O = 3RH + CHOH 



I I 



CH* R CH 2 OH 



One molecule of neutral fat is split into three molecules of fatty 

 acid and one of glycerin. This is the general reaction which occurs 

 in the spoiling of butter or fat due to bacterial activity. 



Proteases, which possess the power of splitting proteins, are 

 widely distributed in bacteria, as is exemplified by their gelatin- 

 liquefying powers. This also is a hydrolytic reaction in which a 

 number of molecules of water is caused to enter the protein molecule 

 with its subsequent breaking down into proteoses, peptones, and 

 finally amino-acid. Even this, as complex a reaction as it is, has 

 been shown to be reversible in at least two cases. 



Zymases, which occur in the yeast cell, are endo-enzymes and 

 their function is to liberate energy for the use of the cell, as is shown 

 by the following table from the work of Rahn : 



ENERGY LIBERATED FROM 1 GRAM OF SUBSTANCE. 



Soluble enzymes. Endozymes. 



Pepsin, trypsin ... calories Lactacidase .... 80 calories 



Lipase ...... 4 " Alcoholase . . . .120 



Maltase sucrase ... 10 " Urease ..... 230 " 



Lactase ..... 23 " Vinegar oxidase . . . 2500 " 



The first zymase isolated from a microorganism was that of 

 urease, or the ferment which converts urea into ammonium car- 



