THE EFFECT OF RADIATIONS FROM A MERCURY ARC IN QUARTZ ON ENZYMES : II. THE EFFECT OF ULTRA-VIOLET RADIATION ON AMYLASE IN SOLUTION

Amylase in solution is inactivated by the radiations from a mercury arc in quartz, in a manner similar to that previously reported for pepsin. The reaction was followed to a point where more than 88 per cent change had taken place, the course being that of mono-molecular radiochemical change. Apparently, this reaction is due to the influence of ultra-violet radiation alone

THE EFFECTS OF RADIATIONS ON BIOLOGICAL SYSTEMS : II. IMMEDIATE AND SUBSEQUENT EFFECTS OF X-RAY IRRADIATION UPON RESPIRATION OF DROSOPHILA LARVAE

By means of measurement of CO2 respiratory rates it has been possible to observe immediate and latent effects of x-ray irradiations upon Drosophila larvae. The observations were extended over a period of several days, the duration of the prepupal period being observed also. In every instance a significant decrease in the rate of CO2 respiration was observed immediately after irradiation. This decrease was univariant with the period of irradiation within the experimental limits

THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES : III. A UNIT OF MEASURE OF ACTIVITY FOR RADIUM EMANATION.

In this communication we have introduced a unit to express activity or power of a given preparation of radium emanation. We have named this unit the curie-power and defined it as the activity of 1 curie of radium emanation and its radioactive products in equilibrium with it. We suggest the introduction of this unit in order that we may make a more comprehensive statement of our experimental observation. In the radiochemical reaction effected by the radiations (beta and gamma) from radium emanation in which enzymes are inactivated the chemical change in a given system is a function of the product of two variables; namely, the average activity of the radium emanation, Pa, expressed in terms of the unit millicurie-power, and time, t, expressed in hours. This product has the dimensions of energy and is identical with W which is measured in terms of the energy unit, millicurie-power hours

THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES : VI. THE INFLUENCE OF VARIATION OF TEMPERATURE UPON THE RATE OF RADIOCHEMICAL INACTIVATION OF SOLUTIONS OF PEPSIN BY BETA RADIATION.

Data are presented which indicate that variation in temperature is associated with only slight variation in the speed of the radiochemical inactivation of pepsin in dilute solution

THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES : IV. THE EFFECT OF RADIATIONS FROM RADIUM EMANATION ON SOLUTIONS OF INVERTASE.

The radiochemical inactivation of invertase by beta radiation from the radioactive products in equilibrium with radium emanation can be explained quantitatively on the same basis as that of trypsin and pepsin previously reported; namely, the rate of change in the logarithm of the concentration of the active enzyme with respect to the variable, W, is constant, under the conditions of irradiation described, when the volume of solution exposed is constant. When, within the limits stated in this paper, this volume (V) is varied, the rate of radiochemical change is inversely proportional to V; i.e., See PDF for Equatio

THE EFFECT OF RADIATIONS FROM A MERCURY ARC IN QUARTZ ON ENZYMES : I. THE EFFECT OF ULTRA-VIOLET RADIATION ON PEPSIN IN SOLUTION.

Pepsin in solution is inactivated by the radiations from a mercury arc in quartz. It would seem that the effective radiations are those in the ultra-violet region of the spectrum. The form of the curve describing the course of the inactivation is the same as that found for monomolecular chemical change

THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES : II. THE EFFECT OF RADIATIONS FROM RADIUM EMANATION ON PEPSIN IN SOLUTION.

Pepsin in solution is inactivated by the radiations (beta and gamma) from radium emanation. This chemical effect has been studied quantitatively. The principles involved in this radiochemical reaction are apparently the same as those found in the case of trypsin previously reported; namely, the change in the logarithm of the concentration of active enzyme varies directly with the variable, W

THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES : V. THE INFLUENCE OF VARIATION OF THE THICKNESS OF THE ABSORBING LAYER OF SOLUTIONS OF PEPSIN UPON THE RATE OF RADIOCHEMICAL INACTIVATION OF THE ENZYME.

Evidence is presented which indicates: (1) that the effect of gamma radiation is negligible with respect to that of beta radiation upon pepsin in dilute solution under the conditions employed in the experiments made; (2) approximately the thickness of fluid layer which may be regarded as necessary and sufficient to practically completely absorb the available beta radiation; (3) that the mean reaction speed coefficient in radiochemical inactivation of pepsin varies inversely with the volume of solution irradiated if the thickness of the fluid layer satisfies the sufficient condition stated in (2), and beyond this as far as has been studied

A VISCOSIMETRIC METHOD OF ESTIMATING ENZYME CONCENTRATION WITH SPECIAL REFERENCE TO AMYLASE

Certain technical modifications of the viscosimetric methods as first employed by Northrop and Hussey have been presented. Most of these have been employed with satisfactory results in the irradiation studies of Hussey and Thompson over a period of several years. These are in turn applied to a method of estimation of amylase concentration

THE EFFECTS OF RADIATIONS ON BIOLOGICAL SYSTEMS : I. INFLUENCE OF HIGH-FREQUENCY X-RAY RADIATION UPON THE DURATION OF THE PREPUPAL PERIOD OF DROSOPHILAE

The effect of high-frequency x-ray irradiation in prolongation of the larval stage of Drosophila melanogaster has been studied further, and evidence presented of the attainment of a maximum effect followed by a decrease to an almost level plateau in the course curve of average (median) prepupal period (φ) as a function of the period of irradiation (t) under otherwise fixed conditions. The variation of effects of the experimental treatment with age of the larvae at the time of irradiation has been demonstrated in both control and irradiated lots, and a strikingly decreased effect observed when ventilation was not supplied as usual. Means of employment of a living system of this type as an indicator of effectiveness of radiation as in phantom depth or other distributional experiments have been presented and their use illustrated