P

Peptide

H₂N-CHR-CO-NH-CHR-COOH
Quick Reference
Formula / NotationH₂N-CHR-CO-NH-CHR-COOH
Also Known AsPolypeptide (longer chain), oligopeptide (3-20), dipeptide (2 AA), protein (folded polypeptide)

What is Peptide?

A peptide is a molecule consisting of two or more amino acids linked together by peptide bonds (amide bonds between the carboxyl group of one amino acid and the amino group of the next). Dipeptides contain two amino acids; oligopeptides contain 3–20; polypeptides contain many (>20). Proteins are polypeptides with a defined three-dimensional structure. Peptides are important in biological signaling and as pharmaceuticals.

Formula & Notation

H₂N-CHR-CO-NH-CHR-COOH

Other Names / Synonyms: Polypeptide (longer chain), oligopeptide (3-20), dipeptide (2 AA), protein (folded polypeptide)

Properties & Characteristics

Formed by condensation reaction: −COOH + H₂N− → −CO-NH− + H₂O. Peptide bond: planar (partial double bond character). N-terminus: free −NH₂. C-terminus: free −COOH. Molecular weight: 200 Da (dipeptide) to >10,000 Da (polypeptide boundary). Hydrolysis by acid, base, or proteases. Isoelectric point: pH where net charge = 0.

Uses & Applications

Pharmaceutical drugs (insulin, oxytocin, vasopressin, cyclosporin). Food flavoring (aspartame is a dipeptide). Biological signaling molecules (hormones, neuropeptides). Antimicrobial peptides. Cosmetic ingredients. Cancer immunotherapy (peptide vaccines). Solid-phase peptide synthesis (SPPS).

Safety Information

Peptide drugs: allergic reactions possible. Recombinant peptides require sterile handling. Synthesis intermediates (coupling reagents like DCC, HOBt) may be toxic. Skin sensitizers possible. Proper handling of biological material required.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Peptide
Formula H₂N-CHR-CO-NH-CHR-COOH
Synonyms Polypeptide (longer chain), oligopeptide (3-20), dipeptide (2 AA), protein (folded polypeptide)

Frequently Asked Questions

A peptide is a molecule consisting of two or more amino acids linked together by peptide bonds (amide bonds between the carboxyl group of one amino acid and the amino group of the next). Dipeptides contain two amino acids; oligopeptides contain 3–20; polypeptides contain many (>20). Proteins are polypeptides with a defined three-dimensional structure. Peptides are important in biological signaling and as pharmaceuticals.

More "P" Terms

View all "P" terms →
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z