Terminal alkyne substituted O-6-benzylguanine for versatile and effective syntheses of fluorescent labels to genetically encoded SNAP-tags

We have developed a terminal alkyne substituted O6-benzylguanine, named PYBG, as a versatile precursor to be facilely conjugated with various fluorescent dyes through 'Click chemistry' and Sonogashira coupling reactions. These fluorescent PYBG derivatives specifically and efficiently label the target genetically encoded SNAP-tags in live cells.