Free-radicals could cause infertility in men

Researchers have isolated an enzyme that protects sperm from attack by free-radicals, which Len Hall, Professor of Molecular Genetics at Bristol University, believes could be lacking in some infertile men.

Scientists have long been intrigued by the finding that men whose partners were having difficulty conceiving often had a high rate of free-radicals in their semen. It was likely that these reactive molecules were damaging sperm but, until now, quite how this might be coming about was unknown. The enzyme known as glutathione peroxidase 5 (GPX5) has been shown to bind to the head of each sperm, forming a protective barrier which the damaging free-radicals cannot penetrate.

If Hall's study is confirmed, abnormally low GPX5 levels in semen could be used to diagnose infertility in some men. Ironically, the findings could also pave the way for a new male contraceptive. Unravelling the structure of GPX5 could allow scientists to design a chemical that interferes with the enzyme's action in fertile men.