Chemists have identified a protein target of a molecule that inhibits parasitic invasion. 

The team led by Nicholas Westwood at the University of St Andrews, UK, and Gary Ward at the University of Vermont, USA, adopted an approach based on finding compounds that prevent live parasites from invading cells, before attempting to discover how the compounds achieve this. By understanding how parasites invade cells, they hope to work towards a cure for diseases such as toxoplasmosis and malaria. 

The team chose to work with conoidin A, which is known to inhibit host cell invasion by the parasite Toxoplasma gondiI. They found that this inhibitor acts on an enzyme produced by the parasite called peroxiredoxin II, although this may not be the invasion relevant target of the inhibitor. Peroxiredoxins are a family of enzymes that function in antioxidant defense and signal transduction. The inhibitor binds covalently to a peroxiredoxin cysteine of TgPrxII, which prevents its enzymatic activity.

The team also found that conoidin A inhibits mammalian peroxiredoxin which could be important as changes in peroxiredoxin II expression are associated with a variety of human diseases, including cancer.