ABSTRACT
Here we report the synthesis and genetic encoding of the lysine post translational modifications, ß-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.
ABSTRACT
We have improved the incorporation of l- and d-forms of unnatural amino acid (UAA) Nε-thiaprolyl-l-lysine (ThzK) into ubiquitin (UB) and green fluorescent protein (GFP) by 2-6 folds with the use of the methylester forms of the UAAs in E coli cell culture. We also improved the yields of UAA-incorporated UB and GFP with the methylester forms of Nε-Boc-l-Lysine (BocK) and Nε-propargyl-l-Lysine (PrK) by 2-5 folds compared to their free acid forms. Our work demonstrated that using methylester-capped UAAs for protein expression is a useful strategy to enhance the yields of UAA-incorporated proteins.