Enzymes 197 



colon form an interesting exception; they all react intensely, 

 even though they may be completely benign histologically. 



Phosphorylase 



Enzymes catalyzing the reaction 



Polysaccharide + inorganic phosphate ^ glucose- 1-phosphate 



(where the polysaccharide may be either starch of glycogen) 

 have been described by Cori and Cori,^^ Kiessling,®^ and 

 Hanes.^' If the reaction is started from the right side, a trace 

 of polysaccharide is needed as a primer; the equilibrium of 

 the reaction depends mainly on the pH. At pH ± 5.7, the 

 equilibrium is shifted to the left; at pH 7-7.6, to the right. 

 Successful attempts at the demonstration of phosphorylase 

 have been made by Yin and Sun^^ and by Cobb.^^ Yin and 

 Sun used sections of starch-free, water-soaked sections of 

 soybean; Cobb used paraffin sections of frozen-dried carti- 

 lage from which glycogen had been removed by saliva. In 

 both cases the tissues were incubated with glucose- 1-phos- 

 phate at pH ±6 for 30 minutes to 6 hours; starch and gly- 

 cogen, respectively, were demonstrated by specific stains. 

 This method deserves further investigation, especially in re- 

 spect to the optimal conditions, of the reaction. 



Zymohexase (Aldolase) 



Allen and Bourne^^ have pubhshed a method for the dem- 

 onstration of zymohexase. It is based on the fact that the 



85. Cori, C. F., and Cori, G. T.: Proc. Soc. Exper. Biol. & Med., 34:702, 

 1936; Cori, C. F. and Cori, G. T.: ibid., 36:119, 1937; Cori, C. F.: Endo- 

 crinology, 26:285, 1940; Cori, G. T., ^nd Cori, C. F.: J. Biol. Chem., 

 135:733, 1940. 



86. Kiessling, W.: Biochem. Ztschr., 298:421, 1938. 



87. Hanes, C. S.: Proc. Roy. Soc. London, B, 128:421, 1940; Hanes, 

 C. S.: ibid., 129:174, 1940. 



88. Yin, H. C, and Sun, C. N.: Science, 105:650, 1947. 



89. Cobb, J. D.: The morphological distribution of glycogen and glyco- 

 proteins in the cells and extracellular materials of growing bones (thesis. 

 University of IlHnois, 1949). 



90. Allen, R. J. L., and Bourne, G. H.: J. Exper. Biol., 20:61, 1943. 



