Does Freezing Damage Peptides?

One of the most common questions in peptide research is whether a reconstituted compound can be frozen to extend its shelf life. The answer is not a simple yes or no.

The Mechanical Stress of Freezing

When water freezes, it expands and forms ice crystals. For many large or complex peptide molecules, these sharp crystals act like "molecular scissors," physically shearing the peptide bonds or causing the molecule to unfold (denature). Once a peptide is denatured, it loses its ability to bind to its target receptor, rendering it biologically inactive.

What about GLP-1 Peptides?

Interestingly, some highly modified peptides like Semaglutide are remarkably robust. In laboratory settings, these molecules have shown a higher tolerance for temperature fluctuations, though pharmaceutical guidelines still recommend avoiding freezing for the final user product to ensure clinical consistency.

Freeze-Thaw Cycles

The most damage often occurs during the freeze-thaw cycle itself. Repeated freezing and thawing is exponentially more damaging than a single deep freeze. If a peptide must be frozen, it should be aliquoted into single-use doses to avoid multiple cycles.