Genetic Encoding of a Photocaged Histidine for Light-Control of Protein Activity.

The use of light to control protein function is a critical tool in chemical biology. Here we describe the addition of a photocaged histidine to the genetic code. This unnatural amino acid becomes histidine upon exposure to light and allows for the optical control of enzymes that utilize active-site histidine residues.

Genetic encoding of isobutyryl-, isovaleryl-, and β-hydroxybutryl-lysine in .

Here we report the synthesis and genetic encoding of the lysine post translational modifications, β-hydroxybutyryl-lysine, isobutyryl-lysine and isovaleryl-lysine. The ability to obtain a homogenous protein samples with site-specific incorporation of these acylated lysine residues can serve as a powerful tool to study the biological role of lysine post translational modifications.

Linkage-Specific Synthesis of Di-ubiquitin Probes Enabled by the Incorporation of Unnatural Amino Acid ThzK.

Di-ubiquitin (diUB) conjugates of defined linkages are useful tools for probing the functions of UB ligases, UB-binding proteins and deubiquitinating enzymes (DUBs) in coding, decoding and editing the signals carried by the UB chains. Here we developed an efficient method for linkage-specific synthesis of diUB probes based on the incorporation of the unnatural amino acid (UAA) N -L-thiaprolyl-L-Lys (L-ThzK) into UB for ligation with another UB at a defined Lys position. The diUB formed by the UAA-mediated ligation reaction has a G76C mutation on the side of donor UB for conjugation with E2 and E3 enzymes or undergoing dethiolation to generate a covalent trap for DUBs.