Catalase activity in equine semen

Objective-To characterize the activity of catalase in equine semen. Animals-15 stallions of known and unknown reproductive history. Procedure-Seminal plasma was collected from raw equine semen by centrifugat ion, and samples of seminal plasma were frozen prior to assay for catalase activity. Tissue samples (n = 3 stallions) from the bulbourethral gland, pr ostate gland, vesicular gland, and testis were homogenized, and cauda epidi dymal fluid was collected for determination of catalase activity. Catalase activity was determined as an enzyme kinetic assay by the disappearance of H2O2 as measured by ultraviolet spectrophotometry. Results-Catalase activity in equine seminal plasma was 989.3 +/- 167.8 U/ml (mean +/- SEM), and the specific activity of catalase in equine seminal pl asma was 98.7 +/- 29.2 U/mg of protein. Specific activity of catalase in ti ssue homogenates was significantly higher in the prostate gland (954 +/- 27 0 U/mg of protein) than in the ampulla (59 +/- 5 U/mg of protein), bulboure thral gland (54 +/- 11 U/mg of protein), vesicular gland (39 +/- 3 U/mg of protein), cauda epididymal fluid (11 +/- 3 U/mg protein), or testis (54 +/- 6 U/mg of protein). Conclusions and Clinical Relevance-Equine seminal plasma contains a high ac tivity of catalase that is derived primarily from prostatic secretions. Pro cedures such as semen cryopreservation remove most seminal plasma from seme n may reduce the ability to scavenge H2O2 and thereby increase the suscepti bility of spermatozoa to oxidative stress.