Effects of Ionizing Radiation on Enzymatic Activity: Case Studies of Invertase and Collagenase

Ionizing radiation affects enzymes, which are essential for most cellular functions, by inducing chemical alterations in their molecular structures, often resulting in the inhibition of their activities. Unraveling the molecular and kinetic mechanisms driving these effects requires irradiation protocols that ensure accurate dose delivery, spatial homogeneity, and reproducibility. In this study, we established a systematic experimental framework that adapts a medical linear accelerator (LINAC) as a precision source for biochemical irradiation experiments. A rigorous protocol was developed that allows enzyme solutions to be irradiated under strictly defined and verifiable dosimetric conditions. Using this approach, we quantified the radiation-induced modulation of enzyme activity in two representative enzymes: invertase (β-fructofuranosidase) and collagenase. For invertase, a pronounced nonlinear decrease in enzyme activity was observed, with the enzyme retaining approximately only 2.2% of its initial activity at 50 Gy. Conversely, collagenase activity exhibited an exponential dose–response behavior over the dose range 0.1–200 Gy, yielding a global inactivation constant of K = 0.015 Gy−1. Complementary SDS–PAGE analysis revealed no detectable radiation-induced protein fragmentation or aggregation under the investigated conditions. These results confirm enzyme-specific radiation sensitivity and demonstrate the efficacy of this LINAC-based methodology for quantitative dose–effect studies. Overall, this work provides a versatile experimental tool for applied radiation research, bridging the gap between clinical medical physics and fundamental biochemistry.