Pharmacology & biology
Protein
A long amino-acid chain, conventionally more than about fifty residues, usually folded into a defined three-dimensional structure.
In plain terms
The distinction between a long peptide and a small protein is a matter of custom, not chemistry. In practice, "protein" implies a molecule large enough to fold into a stable structure with an interior, while "peptide" implies something small enough that its shape is dominated by its surroundings.
Educational reference only. Pepperz does not provide medical advice, diagnosis, treatment, prescribing guidance, or dosing recommendations.