1154 BIOLOGICAL EFFECTS OF RADIATION 



destruction, Agulhon (la) suggests three groups: (a) invertase, laccase, 

 and tyrosinase, destroyed by visible light only when oxygen is present 

 and by ultra-violet more rapidly when oxygen is present; (b) catalase and 

 emulsin, inactivated in a vacuum by both visible and ultra-\dolet radia- 

 tion ; and (c) rennet, destroyed by ultra-violet in the presence or absence 

 of oxygen. The interaction of foreign substances in these effects is 

 recognized as a possibility. 



Chauchard (12) made a quantitative study of the action of mono- 

 chromatic ultra-violet light on amylase of Aspergillus (details of prepara- 

 tion of enzyme are not given). Sparks between electrodes of Mg, Cd, 

 and Zn were used as light sources, filters being used in one case to isolate 

 the various wave-lengths, the enzyme preparation being exposed as a 

 suspension 7 mm. in depth in a quartz cell placed 4 cm. from the light 

 source. In a second part of the experiment the light was separated into 

 monochromatic radiations by two quartz prisms. There was no mention 

 of temperature control. The energy of each wave-length was measured 



o 



with a "Ruben's battery," wave-lengths ranging from 2144 to 3600 A 

 being employed. Absorption studies were made for several wave- 

 lengths. It was concluded that the photochemical action is proportionate 

 to the absorption of the suspension, and absorption varies inversely with 



o 



the wave-length, the greatest absorption being 99.96 per cent at X2307 A 

 (the shortest wave-length employed in the absorption studies). Amylase 

 was destroyed only by radiation of less than 2800 A, the action increasing 

 very rapidly as the wave-length decreases, while lipase was destroyed 

 even by radiations of X3300 A, with shorter wave-lengths increasingly 

 efficient in the inactivation. There seemed to be no relation between 

 the absorption spectrum of pancreas extract, which has a maximum 

 absorption at 2813 A, and the destruction spectra of amylase and lipase. 

 In 1923, Ludwig Pincussen began the publication of a series of papers 

 entitled "Fermente und Licht" which reported a number of experiments 

 conducted by him and his associates upon the subject. Reference can 

 be made here and in later paragraphs to only a limited number of the 

 observations reported. Using malt diastase, the full spectrum of the 

 mercury arc produced strong inactivation, the action depending upon 

 such conditions as the concentration of the solution, on accompanying 

 compounds, and on the reaction of the medium (67a). The greatest 

 effect occurred at the optimum reaction for enzyme activity. Using 

 later (67c?) the same enzyme and the same source of radiation, the reaction 

 constant was calculated at various hydrogen ion concentrations. With 

 increased exposure, the reaction constant decreased. The inactivation 

 constant was also calculated from digestion experiments with various 

 concentrations of starch at different hydrogen ion concentrations. 

 Inactivation was found to follow the course of a monomolecular reaction, 

 with maximum decrease in the reaction constants at pH 6.26. Taka 



