LAUSR

Abstract One of the factors determining the homeostasis of biological systems is the balance between the formation of reactive oxygen species (ROS) and the activity of the antioxidative defence system. Regarding seasonal variations in secretory activity in different parts of roe buck’s (Capreolus capreolus) epididymis, the aim of present study was to compare the expression of selected antioxidative proteins in three periods of the rutting season. Using proteomics methods (2D PAGE , tandem mass spectrometry MS/MS) 5 antioxidative enzymes were identified for the first time in different segments of the epididymis of the roe buck. The highest expression of these enzymes was found in the rutting season. Findings indicated that the antioxidative function of the buck’s epididymis, regardless of the period of the rutting season, but particularly in the rutting season, is maintained mainly because of the presence of three conservative polypeptides: glutathione S-transferase (GST), protein disulfide isomerase A3 (PDIA3), and PDIA3 precursor. Moreover, a protective role against the harmful products of redox reactions is played during the discussed periods by peroxiredoxin-2 (PRDX2), identified in the cauda of the epididymis. In the tissue of the corpus and caput of the epididymis its expression was only found in the rutting season. The expression of biliverdin reductase A (BRVA ) in the epididymis was only observed in the rutting season.