EFFECTS OF RADIATION ON ENZYMES 1153 



cially of the purest invertase preparations. Inaetivation by ultra-violet 

 rays was very pronounced in the presence of ozone. In the presence of 

 molecular oxygon, 10 min. of irradiation caused activation of invertase. 

 This was explained by assuming that the oxygen, activated by ultra- 

 violet rays, oxidized the activity-restraining substances accompanying 

 the enzyme, making the latter harmless. In this work a quartz-mercury 

 lamp was used directly for the radiation studies, and there was room for 

 refinement of technique. 



Gorbach and Lerch (28) irradiated thin layers of invertase solutions 

 of varying degrees of purity in flat dishes, with a mercury-vapor lamp 

 and light filters. The irradiation dishes were placed in a vessel of ice 

 water to prevent heating and evaporation of the enzyme solution. The 

 absorption spectra of all enzyme solutions showed, independent of their 

 degree of purity, an absorption band at 2700 A. Sharpness of the band 

 increases with the degree of purity of the enzymic preparation. Absorp- 

 tion was not measurably changed when the enzyme was first rendered 

 inactive by ultra-violet irradiation. Pure tryptophane was found to 

 absorb at 2700 A, and an increase in the tryptophane, which was present 

 in the purest enzyme preparations, increased the enzyme activity. The 

 investigators conclude that tryptophane is the carrier for the enzyme- 

 active group, and inaetivation of the invertase might be explained, in 

 the case of their experiment, as a disturbance of tryptophane as a usable 

 carrier. The absorption spectra were taken with a Zeiss spectrograph 

 (Scheibe method). Gorbach and Kimovec (27) found that invertase 

 solutions of definite purity which have been irradiated for 10 min. and 

 longer lose their residual activity upon subsequent standing, while 

 enzyme solutions irradiated for a shorter time are stable. No reactiva- 

 tion was obtained by the addition of tryptophane or yeast gums; on the 

 contrary, post-inactivation was hastened, yeast gums acting more power- 

 fully than tryptophane. 



Agulhon (1, la, 2) studied the effects of radiations from a mercury 

 arc upon a number of commercial and crude enzymes, i.e., invertase, malt 

 and pancreatic amylases, emulsin, pepsin, rennet, catalase, laccase, and 

 tyrosinase. An Heraus mercury-vapor lamp in fused quartz, using 2 to 

 3 amp. on 110 v., was used as the radiation source, and the enzyme 

 solutions were exposed at distances of 15 to 20 cm. both in quartz and in 

 glass test tubes, the glass being suflaciently thick to check radiations 

 shorter than 3022 1. After exposures ranging from 30 min. to 6.5 hr., 

 the activity of all of these enzymes suffered some degree of attenuation 

 from wave-lengths shut out by glass but transmitted by quartz. Some 

 deleterious effect of visible rays was noted on emulsin and catalase, but 

 visible light appeared to have no effect upon the other enzymes. In 

 general, the injury appeared to be due to the ultra-violet, with radiations 

 longer than X3022 A having no effect. Considering the mechanism of 



