Histidine side chains in helical structures catalyse-the acylation of
flanking lysine, ornithine and 1,3-diaminobutyric acid residues provid
ed they are in positions i - 3 and i + 4, but not in positions i - 4,
i - 1, i + 2, i + 3, relative to a histidine in position i,in a novel
site-selective functionalization reaction that enhances the potential
of polypeptide and protein design.