Studies on Enzyme Action. 201 



The acceleration brought about by the addition of sugars may be 

 attributed to a withdrawal of water by the sugar and the consequent 

 increase in the amount of the " active system," as pointed out in our 

 previous paper. 



" Studies on Enzyme Action : The Effect of ' Poisons ' on the Kate 

 of Decomposition of Hydrogen Peroxide by Haemase." By 

 GEORGE SENTEB, Ph.D., B.Sc, (Lond.). Communicated by 

 Professor E. H. STARLING, F.Pt.S. Eeceived June 2, 1904. 



Schdnbein* was the first to observe that most animal and vegetable 

 juices have the property of decomposing hydrogen peroxide into water 

 and oxygen, as well as the power of developing a blue colour in 

 tincture of guaiacum containing a little hydrogen peroxide. Since 

 these properties belonged to all the enzymes then known, e.g., emulsin 

 and diastase, Schonbein regarded them as characteristic of enzymes 

 in general, and used them in his numerous investigations as tests for 

 the presence of these bodies. 



A good many years afterwards Jacobson,f working with impure 

 emulsin and pancreatin, showed that the power of these enzymes to 

 catalyse hydrogen peroxide could be destroyed without affecting seriously 

 the specific ferment action. A year or two ago, LoewJ suggested that 

 the power of plant and animal juices to decompose hydrogen peroxide 

 is due to an enzyme of very wide distribution, which he has nsmed 

 catalase. According to this view, Jacobson's impure emulsin contained 

 some catalase, which is less resistant against heat than the emulsin, 

 and can be rendered inactive without affecting seriously the other 

 ferment. 



Since Schonbein's time, the properties which blood possesses of 

 decomposing hydrogen peroxide and of giving the guaiacum reaction 

 have formed the subject of numerous investigations by Schmidt, 

 Bergengriin,|| Spitzer,*! Schar,** Cotton, ft Yille and Moitessier,J| and 

 others, and this is not surprising when we consider the importance 

 of the guaiacum test for the detection of small amounts of blood. 



Spitzer concluded that the guaiacum reaction and the catalysis 



* ' Journ. f. prakt. Chemie,' vol. 89, p. 334 (1863). 



t ' Zeit. f. physiol. Chemie,' vol. 16, p. 340 (1892). 



J Loew, " Catalase," ' U.S. Dept. of Agriculture Eeport,'iN"o.^68, 1901. 



Pfliiger's ' Arcliiv,' vol. 6, p. 413 (1872). 



|| ' Irsaug. Dissertation,' Dorpat, 1888. 

 1" Pfliiger's ' Archiv,' vol. 67, p. 615 (1897). 

 ** ' Zeit. fur Biologie,' vol. 6, p. 467 (1870). 

 ft Cotton, < Bull. Soc. China.,' vol. 25, p. 255 (1901). 

 U ' Bull. Soc. China.' [3], vol. 27, p. 1003 (1902). 

 Loc. tit. 



Q 2 



