Selenocysteine is derivative of which aminoacid -

Ans. is 'a' i.e., Serine o Selenocysteine is considered as 21" standard amino acid. o It is present at the active site of some enzymes that catalyze redox reactions, e.g. thioredoxin reductase, glutathione peroxidase, and the deiodinase (converts thyroxin to triiothyronine). o Biosynthesis of selenocysteine requires cysteine, serine, ATP and a specific t-RNA o Serine provides the carbon skeleton of selenocysteine. o Selenocysteine has a structure similar to cysteine, but containing the trace element selenium in place of sulfur atom of cysteine.