Effect of Ionizing Radiation on the Activity of the Enzyme Invertase Studied by Polarimetry

The effect of ionizing radiation on biological systems, and particularly the enzymes which are responsible for most cellular functions, leads to chemical alterations in their molecular structure, and as a subsequent result often causes inhibition of their activities. Of particular importance for understanding the molecular and kinetic mechanisms of action of ionizing radiation on these systems is to find suitable experimental protocols and kinetic models applicable to specific enzymes and their substrates. In the present study we offer a convenient experimental approach by applying polarimetric measurements to study the influence of ionizing radiation on the catalytic action of the enzyme invertase. Following the Michaelis- Menten kinetic model we determined the values of the kinetic constants Km и Vmax for the reactions catalyzed either by the native or irradiated invertase and made some conclusions about possible changes either in the active centre or in the molecular structure of the enzyme under the action of ionizing radiation.