Peptide Therapeutics|Intermediate4 min

How Peptide Synthesis Works (SPPS)

Watch the Merrifield solid-phase peptide synthesis cycle in action — from resin bead to finished peptide drug. Understand the chemistry that powers the GLP-1 revolution.

How Peptide Synthesis Works (SPPS)

Fmoc chemistry · from bead to pure peptide

Step 1 of 6

The Solid Support

A polystyrene resin bead

Solid-phase peptide synthesis (SPPS) was invented by Bruce Merrifield in 1963 and earned him the 1984 Nobel Prize. The trick: build the peptide while it is anchored to an insoluble bead so that excess reagents and by-products can simply be washed away.

The support is typically a cross-linked polystyrene resin (or PEG-based resin like ChemMatrix) with a chemical linker on its surface. The linker is chosen so the peptide can be cleaved off cleanly at the end.

All of the chemistry happens heterogeneously — the bead is suspended in solvent, reagents flow in, waste flows out.

Key Point

SPPS works because the peptide is tethered to something you can filter — washing replaces purification between every step.

Loading animation...

What You'll Learn

1Why Merrifield's solid-phase approach replaced solution synthesis
2The Fmoc deprotection–coupling cycle that builds peptides one residue at a time
3How side-chain protecting groups prevent unwanted side reactions
4Why SPPS creates a manufacturing bottleneck for GLP-1 drugs

Use this explainer

Share this visual explainer with students, colleagues, or on your blog. Link back to help others discover it.

How GLP-1 Drugs Work (Ozempic, Wegovy, Mounjaro)

How Cell-Penetrating Peptides Deliver CRISPR

More Visual Explainers

Gene EditingBeginner3 min

How Peptide Synthesis Works (SPPS)