Tellurocysteine
Tellurocysteine is an amino acid with the formula. It is the heavy analogue of serine, cysteine, and selenocysteine. Tellurol is a rare and fragile functional group, especially alkyl derivatives. The C-Te bond is weak compared to 234 kJ/mol for the C-Se bond. These factors combine to make tellurocysteine very labile. Even selenocysteine occurs only rarely in nature. Instead of tellurocysteine, tellurocystine is generally isolated instead. Tellurocystine has the formula, with a central Te-Te bond.
Properties
The fungus Aspergillus fumigatus is capable of incorporating tellurocysteine into proteins when grown in appropriate media.When incorporated into glutathione transferase, tellurocysteine efficiently inhibits aminoacylation and increases the efficiency of glutathione peroxidase.