224 IMMUNO-CATALYSIS 



with Weidenhagen's theory hydrolyzed melibiose and also the above 

 mentioned a-o-galactosides. y^-Methyl-L-arabinoside ([a]-"D+236°) 

 which has the same configuration as a-methyl-D-galactoside C[a]^*'D+ 

 196°) was likewise hydrolyzed by a-o-galactosidase. ^S-D-galactosidase 

 had no effect on the a-o-galactosides. 



The purest invertase preparation, from brewer's yeast, contained a 

 small amount of /?-D-glucosidase which was capable of hydrolyzing 

 amygdalin (i3-[d-mandelic nitrilej-gentibioside, gentiobiose (;8-gluco- 

 sido-6-glucose) and iS-phenyl-o-glucoside. But this enzyme was not 

 capable of hyrolyzing cellobiose C/3-glucosido-4-glucose) or lactose 

 (4-)8-D-galactopyranosido-D-glucose). 



Invertase preparations from both brewer's and baker's yeast contained 

 small amounts of a new enzyme, a jS-D-mannosidase, which hydrolyzed 

 )8-phenyl-D-mannoside. 



No evidence was obtained to indicate the hydrolysis by the purified 

 invertase preparations of an a-D-fructofuranoside (isosucrose) or of 

 any /3-D-galactoside, a-D-glucoside (including the a- and /?- dextrins), 

 or a-D-mannoside. Melizitose and a-methyl-D-manno-D-gala-heptoside 

 also were not hydrolyzed. 



The above findings are in substantial agreement with Weiden- 

 hagen's theory of the specificity of carbohydrases (p. 151). 



Certain Pwperties of Invertase. The lability of invertase increases 

 with its degree of purity. Invertase has a molecular weight of about 

 20,000, an isoelectric point of pH 5.0. It is inactivated in alkaline 

 medium. In solution it is most stable at pH 4 to 5. It is reported that air 

 dried yeast may be heated in vacuo to 140° to 150°C. without destroy- 

 ing all of the invertase. 



The kinetics appear to be independent of the degree of purity and the 

 condition of invertase preparations. They are the same for the enzyme 

 in the living cell as for a solution of the enzyme. The molecules of 

 invertase are equally active in free and in an adsorbed form (Neuberg, 

 1946; Griffin and Nelson, 1916; Michaelis, 1921). 



a. Antibody Against Invertase. Schubert (1933), in the laboratory 

 of Prof. J. M. Nelson of Columbia University, studied the contro- 

 versial question of whether or not invertase is a protein. 



Invertase was prepared by extracting the autolyzed yeast QSac- 

 charomyces cerevisiae') with water and purified by adsorption on 

 kaolin and elution. It manifested characteristic protein properties. 



