The dehydrogenase PylD catalyzes the ultimate step of the pyrrolysine pathway by
converting the isopeptide L-lysine-Nε-3R-methyl-D-ornithine to the 22nd
proteinogenic amino acid. In this study, we demonstrate how PylD can be
harnessed to oxidize various isopeptides to novel amino acids by combining
chemical synthesis with enzyme kinetics and X-ray crystallography. The data
enable a detailed description of the PylD reaction trajectory for the
biosynthesis of pyrroline and tetrahydropyridine rings as constituents of
pyrrolysine analogues.
