Comparison of protective properties of resveratrol and melatonin in the radiation inactivation and destruction of glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase.

This work investigates the effect of resveratrol and melatonin on structural and functional changes of two enzymes, lactate dehydrogenase (LDH) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), exposed to radiation-induced reactive oxygen species. Solutions of dehydrogenases with or without antioxidants (resveratrol or melatonin) were irradiated with X-rays under the atmosphere of air and at room temperature (21 ± 2 °C). In order to determine the protective effect of melatonin and resveratrol in radiation-induced damage to GAPDH and LDH spectroscopy and HPLC methods were used. Furthermore, plausible binding sites of melatonin or resveratrol to the GAPDH or LDH molecule were analysed. Resveratrol shows better protective properties in the inactivation of GAPDH when compared to melatonin. LDH does not contain ‒SH groups in its active site, and is not inactivated by water radiolysis products other than hydroxyl radicals or the secondary radicals of the studied low-molecular-weight compounds. Resveratrol and melatonin protected the structure of LDH to a greater extent than GAPDH. This difference can be attributed to the fact that LDH potentially binds more resveratrol or melatonin molecules (27 binding sites for resveratrol and 40 for melatonin) than GAPDH (10 binding sites for resveratrol and 18 for melatonin).