Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal leucyl-tRNAs, orthogonal leucyl-aminoacyl-tRNA synthetases, and orthogonal pairs of leucyl-tRNAs/synthetases, which incorporate photoregulated amino acids, OMe-L-tyrosine, .alpha.-aminocaprylic acid, or o-nitrobenzyl cysteine into proteins are proteins are provided in response to an amber selector codon. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with a photoregulated amino acid, Ome-L-tyrosine, .alpha.-aminocaprylic acid, or o-nitrobenzyl cysteine using these orthogonal pairs.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
 This invention was made with government support under Grant GM62159 from the National Institutes of Health and Grant ER46051 from the Department of Energy. The government may have certain rights to this invention.