OXIDASES OR OXIDISING ENZYMES. 



THE general course of the action of the enzymes or 

 unorganised ferments is understood to be one of 

 hydrolysis, or decomposition of the bodies attacked by them 

 with the preliminary taking up of water into their mole- 

 cule. Thus the first action of diastase on starch has been 

 approximately expressed by the equation — 



«C 12 H 20 O 10 + H 2 = n - iC 12 H 20 O 10 + C 12 H 22 O n ; 

 that of invertase on cane sugar 



C 12 H 22 O n + H 2 = CeH.A, + C 6 H 12 O ; 

 that of emulsin on amygdalin 



C 20 H 27 NO U + 2H0O = QH3COH + HCN + 2 (C 6 H 12 6 ). 

 Though no such equation can be written in the case of the 

 action of pepsin on albumin or other proteids there is reason 

 to think this also is one of hydrolysis. The most notable 

 exception so far known is that of myrosin, which splits up 

 sinigrine into sulphocyanate of allyl, potassic-hydrogen- 

 sulphate and sugar, without the intervention of water. 



During the last few years the researches of the French 

 school of physiological chemists have indicated the exist- 

 ence of another group of enzymes, which act by promoting 

 direct oxidation of various substances, chiefly aromatic com- 

 pounds. As these enzymes appear to be distributed some- 

 what widely in the vegetable kingdom, the course of ferment 

 action cannot be restricted to the single process of hydro- 

 lysis. This need not excite surprise, however, for we have 

 long been familiar with micro-organisms which have an 

 oxidising power. Such are the Mycoderma aceti, which 

 forms acetic acid from alcohol, and the organisms in the soil 

 described by Winogradsky and by Warrington, which form 

 nitrous and nitric acids from ammonia. 



LACCASE. 



Of these oxidases, as the enzymes under discussion may 

 be termed, the earliest one recognised was laccase, the body 



