66 PHYSIOLOGY OF YEASTS 



Bau 1 has shown that amygdalase and emulsin are present in Froh- 

 berg yeast. Experiments with Saaz yeast indicated amygdalase, but 

 no emulsin. S. Ludwigii, a yeast with no maltase, acted toward 

 amygdalin as did Frohberg yeast. This seems to indicate that the 

 disaccharide complex of amygdalin is not identical with maltose though 

 it contains two dextrose residues. Bokorny 2 determined the presence 

 of amygdalin in brewers' yeast by the odor of oil of bitter almonds 

 in incubating a mixture of yeast and amygdalin. The existence of 

 a yeast myrosinase was also indicated by yeast and myrosin. The 

 glucosides, arbutin, ciniferin, and salicin, were not changed by the 

 yeast. Farber 3 stated that amygdalase, prunase and oxynitrilase, 

 the three enzymes necessary for the complete hydrolysis of amyg- 

 dalin, could be separated from bottom yeast. 



Oxidizing and Reducing Enzymes 



Catalases are enzymes which decompose hydrogen peroxide with 

 the formation of inactive molecular oxygen. They seem to play a 



2 H 2 O 2 = H 2 + 2 



role in regulating the production of hydrogen peroxide and prevent- 

 ing an accumulation of it. Buchner was the first to detect catalase 

 in yeast juice. 



The investigations of Tolomei, Issajew, 4 Low 5 Henneberg, Neu- 

 mann and Wender, have confirmed the existence of this enzyme. 

 According to Neumann and Wender, two catalases exist in yeast, 

 an a-catalase insoluble (?) in water and a /3-catalase soluble in water. 

 These enzymes, which are found in yeast juice and in yeasts killed by 

 antiseptics, decomposed hydrogen peroxide with the formation of free 

 oxygen. 



Another enzyme similar to catalase, pkilothion, has been pointed 

 out by Rey-Pailhade. It decolorized methylene blue and indigo car- 

 min and transformed the sulfur in hydrogen sulfide, and the icdin 

 in hydriotic acid. Grliss 6 has observed this same enzyme and called 

 it hydrogenase. 



1 Bau, A. Behavior of amygdalin towards fermentation organisms. Wo- 

 chenschr. Brau. 34, 29-31 (1917); Chem. Absts. 12, 403 (1918). 



2 Bokorny, T. Emulsin and myosin in the compressed yeast from Munich 

 brewery, partly also in baker's yeast. Biochem. Zeit. 75, 376-416. 



3 Farber, E. Occurrence of emulsin-like enzymes separable from yeast cells 

 in bottom yeast; also, the absence of myrosine in Berlin top and bottom yeast. 

 Biochem. Zeit. 78, 264-72. Chem. Absts. 11, 1658 (1917). 



4 Issajew, W. Ueber Hefen Katalase. Zeit. physiol. Chemie, 44, 1905. 



6 Low, O. Zur Unterscheidung zwei Arten Katalase. Cent. Bakt. 10, 1903. 

 6 Griiss, J. Ueber Oxydaseerscheinungen der Hefe. Woch. fur Brauerei, 17, 

 1903. 



