Fmoc-Arg(Pbf)-OH-13C6,15N4 is the 13C-labeled and 15N-labeled Fmoc-Arg(Pbf)-OH (HY-Y1636). Fmoc-Arg(Pbf)-OH is an arginine derivative containing amine protecting group Fmoc. Fmoc-Arg(Pbf)-OH is a building block for the introduction of Arg into SPPS (Solid-Phase Peptide Synthesis)[1][2][3].