CATALASE 23 



who found that the hydrolysis was really a saponification 

 effected by the presence of alkali and that only alkaline milks 

 showed the presence of salolase. Rullman, in 1910, proved 

 that milk obtained with aseptic precautions did not give the 

 salol splitting reaction. It has been suggested that salolase is 

 of bacterial origin, although this view is unsupported by experi- 

 mental data. 



Peroxidases. Although Rullman has found traces of sub- 

 stances in milk capable of effecting oxidation by utilisation of 

 atmospheric oxygen (true oxidases), the peroxidases are much 

 more important. These ferments decompose hydrogen perox- 

 ide in accordance with the equation H202 = H20+O. The 

 presence of nascent oxygen is ascertained by the addition of 

 some substance which undergoes a colour change on oxidation 

 (a chromogen). Benzidine, guiacol, ortol, amidol, p. pheny- 

 lenediamine, and phenolphthalin have been employed for this 

 purpose. Kastle and Porch 32 showed that the power of milk 

 to induce the oxidation of phenolphthalin and other leuco 

 bases by hydrogen peroxide is greatly intensified by the addi- 

 tion of certain substances of the phenol type. 



Catalase. Catalase (Loew) or superoxidase (Raudnitz) 

 like peroxidase has the property of decomposing hydrogen 

 peroxide, but, instead of atomic oxygen being produced and 

 absorbed by some compound present, molecular oxygen is 

 formed and may be collected in the gaseous form. 



Some authors have included catalase with the reductases in 

 accordance with the view that the oxygen liberated is utilised in 

 an oxidation process and that the reaction is essentially one of 

 the reduction of hydrogen peroxide to water. There is, how- 

 ever, as little basis for the inclusion of catalase with the reduc- 

 tases as with the peroxidases, for, although its action is inter- 

 mediate between the two, it is entirely independent of them 

 and well-defined in character. 



