Reactive oxygen species block sperm-egg fusion via oxidation of sperm sulfhydryl proteins in mice

Biol Reprod. 1996 Nov;55(5):1063-8. doi: 10.1095/biolreprod55.5.1063.


The effects of reactive oxygen species (ROS) on mouse sperm-egg fusion were determined. Sperm were treated with superoxide and hydrogen peroxide generated by addition of xanthine oxidase (XO: 10-200 mlU/ml) to hypoxanthine (HX: 1 mM). While XO at concentrations higher than 100 mlU/ml decreased the motility and lipid peroxidation of sperm, XO at less than 50 mlU/ml had no such effect. However, 20-50 mlU/ml XO significantly suppressed sperm fusion with zona-free eggs. Two ROS scavengers, superoxide dismutase and catalase, attenuated the inhibition of sperm-egg fusion by HX-XO. The sulfhydryl (SH) reductant, dithiothreitol, also reversed the inhibition. The sperm SH-rich fusion-related proteins were highly sensitive to ROS. These results suggest that ROS at low concentrations may inhibit sperm-egg fusion via oxidation of the SH-proteins in the sperm membrane, without causing loss of motility.

MeSH terms

  • Animals
  • Catalase / pharmacology
  • Dithiothreitol / pharmacology
  • Exocytosis / drug effects
  • Female
  • Hydrogen Peroxide / pharmacology
  • Lipid Peroxidation / drug effects
  • Male
  • Mice
  • Mice, Inbred ICR
  • Oxidation-Reduction
  • Reactive Oxygen Species*
  • Sperm Motility / drug effects
  • Sperm-Ovum Interactions / drug effects*
  • Spermatozoa / chemistry*
  • Spermatozoa / drug effects
  • Spermatozoa / physiology
  • Sulfhydryl Compounds / chemistry*
  • Superoxide Dismutase / pharmacology
  • Superoxides / pharmacology
  • Xanthine Oxidase / metabolism
  • Xanthine Oxidase / pharmacology


  • Reactive Oxygen Species
  • Sulfhydryl Compounds
  • Superoxides
  • Hydrogen Peroxide
  • Catalase
  • Superoxide Dismutase
  • Xanthine Oxidase
  • Dithiothreitol