What is the Fmoc strategy in SPPS?

SPPS is the peptide synthesize based on the solid support which is also known as resin, linkers are modified on the resin to provide the reactive group for the first amino acid. Peptide is synthesized through the amide bond between the amide group and carboxyl group from another in the condition of pre-activated species or in situ activation. To avoid the undesired reactions, protecting groups are involved to temporary mask reactive groups on both N α-position and side chain of the amino acid. Fmoc is one of commonly used N α-position protecting group, which advantages are quiet obvious. For instance, the deprotection condition with 20–50% piperidine in DMF is truly mild; and the protection scheme with the side chain of different amino acid is orthogonal. Moreover the progress of each deprotection reaction can be followed by real time spectrophotometric monitoring the release of the cleaved Fmoc-group at 300-320 nm. After the desired peptide is synthesized, the resin bound peptide is deprotected and detached from the solid support via TFA cleavage since Fmoc-strategy uses acid liable linkers.