What is a peptide?
Answer
A peptide is a chain of two or more amino acids joined by peptide bonds. Peptides are often described as shorter than proteins, although the exact boundary is a scientific convention rather than a rigid rule.
Detailed Explanation
A peptide bond is the amide linkage formed between the carboxyl group of one amino acid and the amino group of another. Short chains may be called dipeptides, tripeptides, or oligopeptides; longer chains are often called polypeptides. A commonly used rule of thumb places peptides at roughly 2–50 amino-acid residues, but structure and function also matter when distinguishing peptides from proteins. In laboratory research, synthetic peptides are used to study molecular recognition, receptor signaling, enzyme activity, analytical methods, and stability.