1152 BIOLOGICAL EFFECTS OF RADIATION 



produced first an increase followed by a decrease in activity. He con- 

 cludes, therefore, that the destructive rays are in the ultra-violet region, 

 while radiation in the red and blue regions has the power of increasing 

 the diastatic activity; this last he explained by assuming the conversion 

 of zymogen into the active enzyme by those wave-lengths. Similar 

 results were obtained with living leaf tissue, except that the effects were 

 less marked. Green attributes this fact to the protective action of 

 chlorophyll and of proteins of the protoplasm against the destructive 

 ultra-violet rays. 



Emmerling (21) likewise studied the effect of sunHght upon a number 

 of crude enzyme preparations but failed to obtain uniform results. Pro- 

 nounced inactivation occurred with rennet and maltase upon an exposure 

 of 6 hr. to direct sunhght, but little or no inactivation occurred upon 

 similar exposures of invertase, lactase, emulsin, amylase, trypsin, and 

 pepsin. Von Tappeiner (82) studied the effects of sunlight upon enzymes 

 with and without addition of fluorescing dye substances, and he found 

 that there was little or no effect upon diastase, invertase, and papain 

 when exposure was made without a fluorescing substance. But when 

 such a substance was added, even in so dilute a concentration as 1 : 1,000,- 

 000, definite attenuation of enzyme activity resulted. In confirmation 

 of these results, Jodlbauer and von Tappeiner (42) exposed solutions of 

 invertase to sunlight with and without ultra-violet rays, and found that 

 the sunlight without the ultra-violet was capable of producing little 

 injury. This injury, however, was increased to 80 per cent in 10 min. 

 if a small amount of fluorescing material was added. The same authors 

 later (86), using a carbon arc, irradiated solutions of invertase in a water 

 bath to exclude infra-red rays and found definite injury from the irradia- 

 tion wholly unrelated to the presence of oxygen of the air. 



Chauchard and Mazoue (14) irradiated solutions of malt amylase 

 and yeast invertase separately and together, using as a Ught source a 

 110-v. mercury-vapor lamp. The enzyme solutions were commercial 

 malt extract and invertase prepared from beer yeast, filtered until clear 

 (details of preparation not given). They were exposed in quartz tubes, 

 fastened to the circumference of a wheel rotating around the lamp at a 

 distance of 12 cm. Activity of both enzymes was diminished, but the 

 malt amylase was found to be much more sensitive to the ultra-violet rays 

 than the yeast invertase. Svanberg (80) using for the first time highly 

 purified invertase solution found its activity to be easily destroyed by 

 ultra-violet light, the destructive effect being considerably greater with 

 increasing purity of the preparation. These results are confirmed by 

 Gorbach and Pick (29) who report that yeast autolysates were scarcely 

 injured by irradiation of 2 hr., while preparations of a high degree of 

 purity lost their activity after 20 to 30 min. The hydrogen ion concentra- 

 tion was found to be of slight effect on the degree of inactivation, espe- 



