Peptide

A peptide is a molecule formed when two or more amino acids are joined by covalent peptide bonds — the same amide linkages that build proteins. The defining feature of a peptide versus a protein is length: peptides are typically short, ranging from two amino acids (a dipeptide) to roughly fifty residues. Beyond that threshold the molecule is conventionally classified as a polypeptide or a protein, although the boundary is set by convention rather than chemistry. Peptides are described by their amino acid sequence, written in single-letter or three-letter code from the N-terminus (free amino group) to the C-terminus (free carboxyl group). Each residue contributes a side chain whose physical and chemical properties — charge, polarity, hydrophobicity, hydrogen-bonding capacity — determine how the peptide folds and how it interacts with other molecules. Peptides are produced biologically by ribosomal translation or non-ribosomal peptide synthetases, and synthetically by solid-phase peptide synthesis (SPPS), the method that underpins almost all research-grade material today. In a research setting, peptides are valuable because they sit at a molecular size where they can be both highly specific in binding and chemically defined enough for reproducible study, which is why so much biochemical and biophysical research is built around them. Peptra Labs supplies these peptides for laboratory research use only, with batch-level HPLC purity and mass-spectrometry identity confirmation documented on each Certificate of Analysis.