Detailed Explanation
A single amino acid unit within a peptide or protein chain. The term 'residue' is used instead of 'amino acid' because each amino acid loses a water molecule (H₂O) when it forms a peptide bond — what remains in the chain is the residue of the original amino acid. Each residue contributes approximately 110–130 Da to the peptide's molecular weight (minus 18 Da for the water lost).
A 51-residue peptide like insulin has 50 peptide bonds. Residues are numbered from the N-terminus (residue 1) to the C-terminus. When scientists say a mutation is at 'position 34' or discuss 'Lys26,' they are referring to specific residues within the peptide chain.
Key Facts
- A single amino acid unit within a peptide or protein chain.
- The term 'residue' is used instead of 'amino acid' because each amino acid loses a water molecule (H₂O) when it forms a peptide bond — what remains in the chain is the residue of the original amino acid.
- Each residue contributes approximately 110–130 Da to the peptide's molecular weight (minus 18 Da for the water lost).
- A 51-residue peptide like insulin has 50 peptide bonds.
- Residues are numbered from the N-terminus (residue 1) to the C-terminus.
- When scientists say a mutation is at 'position 34' or discuss 'Lys26,' they are referring to specific residues within the peptide chain.
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PeptideDefinition.com provides educational content about peptide science. Not medical advice. Consult a licensed healthcare provider for medical decisions.