title: Catalase activity in equine semen.
abstract: OBJECTIVE
  To characterize the activity of catalase in equine semen.
  
  
  METHODS
  15 stallions of known and unknown reproductive history.
  
  
  METHODS
  Seminal plasma was collected from raw equine semen by centrifugation, and samples of seminal plasma were frozen prior to assay for catalase activity. Tissue samples (n = 3 stallions) from the bulbourethral gland, prostate gland, vesicular gland, and testis were homogenized, and cauda epididymal 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 +/- 1678 U/ml (mean +/- SEM), and the specific activity of catalase in equine seminal plasma was 98.7 +/- 29.2 U/mg of protein. Specific activity of catalase in tissue homogenates was significantly higher in the prostate gland (954 +/- 270 U/mg of protein) than in the ampulla (59 +/- 5 U/mg of protein), bulbourethral 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
  Equine seminal plasma contains a high activity of catalase that is derived primarily from prostatic secretions. Procedures such as semen cryopreservation that remove most seminal plasma from semen may reduce the ability to scavenge H2O2 and thereby increase the susceptibility of spermatozoa to oxidative stress.
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis 95616, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Ball
authors.forename: C G
authors.initials: CG
authors.lastname: Gravance
authors.forename: V
authors.initials: V
authors.lastname: Medina
authors.forename: J
authors.initials: J
authors.lastname: Baumber
authors.forename: I K
authors.initials: IK
authors.lastname: Liu
mesh_terms: D000640:Amitrole / Q000494:pharmacology; D000818:Animals; D002374:Catalase / Q000032:analysis*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006736:Horses / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D012661:Semen / Q000201:enzymology*; D019810:Sodium Azide / Q000494:pharmacology; D013056:Spectrophotometry, Ultraviolet / Q000662:veterinary; D013094:Spermatozoa / Q000201:enzymology
chemical_list: D004791:Enzyme Inhibitors; D019810:Sodium Azide; D006861:Hydrogen Peroxide; D002374:Catalase; D000640:Amitrole