FmocSPPS

Fmoc SPPS, or fluorenylmethyloxycarbonyl solid-phase peptide synthesis, is a widely used approach to assemble peptides on a solid support. An N-terminal amino group is protected with the Fmoc group, which is removed under basic conditions (typically 20% piperidine in DMF). The C-terminus is attached to a resin, such as Wang resin for peptides with a free C-terminus or Rink amide resin for C-terminal amides. Side-chain protections are maintained throughout the assembly and are removed during final cleavage with a harsh acid.

The assembly proceeds in iterative cycles: deprotection of the N-terminus, washing, activation and coupling of the next Fmoc-protected amino acid, and repetition until the sequence is complete. Activation is commonly achieved with coupling reagents such as HBTU, HATU, or DIC with HOAt or related additives. After the final amino acid is coupled, the peptide is cleaved from the resin and globally deprotected with a trifluoroacetic acid–based cocktail, often containing scavengers to minimize side reactions.

Fmoc SPPS is compatible with automation and parallel synthesis, enabling rapid generation of peptide sequences on a large scale. Common advantages include mild, base-catalyzed deprotection and good yields for many sequences, as well as straightforward purification after resin cleavage. Limitations include risk of incomplete coupling, aspartimide formation, and racemization at sensitive residues, particularly in longer or highly hindered sequences. The method is widely used to prepare natural and modified peptides, peptidomimetics, and peptide libraries for research and pharmaceutical development.