Fmoc-Gly-Gly-Ser(psi(Me,Me)Pro)-OH is an Fmoc-protected Gly-Gly-Ser pseudoproline-containing tripeptide fragment for solid-phase peptide synthesis (SPPS). The Ser residue is temporarily converted to a 2,2-dimethyloxazolidine pseudoproline, while the upstream Gly-Gly sequence is already present as part of the protected fragment.

The pseudoproline acts as a reversible backbone modification during chain assembly. Acidic final cleavage opens the oxazolidine and restores native Ser, so the final peptide contains the intended Gly-Gly-Ser sequence rather than a retained pseudoproline modification.

Product Information

Why Use a Preformed Gly-Gly-Ser Fragment

This reagent installs a three-residue Gly-Gly-Ser unit rather than a conventional dipeptide. The Gly-Gly amide sequence is already formed, and Ser is carried as the pseudoproline. That distinction matters for both nomenclature and coupling planning. This should be considered alongside difficult SPPS troubleshooting when diagnosing sequence-dependent assembly problems.

Use in Gly-Rich Flexible Regions

Gly-rich segments are conformationally flexible, but flexibility does not prevent aggregation elsewhere in a long resin-bound chain. Positioning a reversible Ser pseudoproline after Gly-Gly can provide a local backbone interruption while preserving the native three-residue sequence after cleavage.

Fragment Coupling Considerations

A protected tripeptide is larger than a single amino acid or standard pseudoproline dipeptide. Coupling efficiency should therefore be evaluated in the context of resin loading, sequence environment, reagent system, and steric accessibility at the growing N-terminus.

Final Cleavage and Ser Recovery

The pseudoproline ring is opened under standard acidic global cleavage, regenerating Ser. The final target therefore contains Gly-Gly-Ser rather than a permanent oxazolidine modification. Related motifs can be compared in the pseudoproline building block series.

Experimental Planning

Fragment size, resin loading, solvent access, and the position of the Gly-Gly-Ser unit can all affect coupling performance. A preformed fragment can simplify local sequence assembly, but it should still be treated as a sequence-specific synthetic choice rather than a universal replacement for stepwise coupling.

For projects where building-block selection needs to be evaluated with the full target sequence, our sequence-specific peptide synthesis can support integrated planning, synthesis, purification, and QC requirements.

Product Documents

MSDS - Fmoc-Gly-Gly-Ser(psi(Me,Me)Pro)-OH (AS4150)

The Safety Data Sheet provides product identification, hazard information, handling and storage guidance, exposure controls, transport information, and regulatory information for laboratory use.

Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.

Frequently Asked Questions

Is this product a dipeptide?

No. It is a protected Gly-Gly-Ser pseudoproline-containing tripeptide fragment. It is listed in the pseudoproline category because the Ser residue is carried in the same reversible pseudoproline form used in the dipeptide series.

Why is Ser incorporated as a pseudoproline?

The temporary oxazolidine changes local backbone hydrogen-bonding and conformation during SPPS. This can be useful when a Gly-Gly-Ser-containing sequence becomes difficult to assemble on resin.

Does the final peptide retain the pseudoproline?

No. Standard acidic global cleavage opens the ring and regenerates native Ser.

Does a preformed tripeptide always couple like an amino acid?

No. A larger protected fragment can have different steric and solubility behavior. Coupling conditions should be evaluated for the specific resin-bound sequence.

Research Use Only.