A new pyridoxal-5-phosphate （PLP） derivative FHMDP was developed for the transamination of different pep- tides with three most hindered amino acid residues （Leu, Ile, Val） as their N-terminus. Compared to the previously reported reactions of PLP derivatives, the N-terminus transamination could be accomplished efficiently with the new compound.
Protein chemical synthesis usually relies on the use of native chemical ligation that couples peptide thioester with a Cys-peptide. A limitation of this method is the difficulty of finding an appropriate Cys ligation site in many synthetic targets. To overcome this problem, the ligation-desulfurization approach has been developed. This approach involves the use of a thiol-containing amino acid as the ligation partner. After the sequence assembly is completed, the thiol group is removed through a desulfurization reaction to generate the standard amino acids. Currently this strategy has been applied to the ligations at a number of amino acids including Ala, Phe, Val, Lys, Thr, Leu, Pro and Gin. The present article reviews the design and svnthesis of these thiol-containing amino acids for native chemical libation at non-Cys sites.
