no 



E. S. GUZMAN BARRON 



ished inhibition of urease by y radiation (Table VI). Destruction of 

 H2O2 by catalase, diminished the degree of inhibition of phosphoglyc- 

 eraldehyde dehydrogenase by a particles, and suppressed the inhibition 

 by /S particles. The combination of nitrogen mustards with — SH groups 



TABLE IV 



Effect of X-Rays on the Activity of Phosphoglyceraldehyde Dehydrogenase. 



Buffer, phosphate, pH 7.0. Enzyme activity, K=z — X where t, time 



t CoC 



in minutes; Co (DPN) initial; C (DPN) at time t. 



TABLE V 



The Effect of a (Po), /? (Sr^"), and y (Ra) Radiation on the Activity of 

 Phosphoglyceraldehyde Dehydrogenase. Enzyme, 20y ; phosphoglyceralde- 

 hyde, 4X10-' M; DPN, 2.5X10-^ M; NaHASO^, 6X10-' M; pyro- 

 phosphate buffer, pU 8.5, 3X10"^ M. Temp. 26°. 



