A general method is proposed that permits incorporation of a photocaged selenocysteine residue in any desired position(s) of a protein utilizing UAG codon suppression by a genetically modified yest strain. The protein carrying the selenocysteine residue(s) caged with photoreactive nitrobenzyl group is expressed and purified from the yest cells. The caging group is removed by illumination with UV light leaving the selenocysteine in place (inside cells or in purified protein preparation). The proposed method has a potential to simplify the synthesis of selenoproteins and therefore expand their biotechnological and biopharmaceutical utilization.
