Fmoc-Gly-Gly-Gly-Gly（Cat No.:L040503）is a tetrapeptide composed of four glycine residues protected at the N-terminus with a 9-fluorenylmethyloxycarbonyl (Fmoc) group. As a flexible, uncharged peptide sequence, it is frequently used in peptide synthesis as a spacer, linker, or model peptide in structural and biochemical studies. The absence of side chains in glycine imparts high conformational flexibility, making this peptide ideal for applications requiring minimal steric hindrance. The Fmoc group enables compatibility with standard Fmoc-based solid-phase peptide synthesis (SPPS), and can be easily removed under mildly basic conditions for further peptide elongation or modification.