Detailed Explanation
Two-dimensional graph of backbone dihedral angles φ (phi) and ψ (psi) showing the sterically allowed conformations for amino acid residues in a peptide chain. Developed by G.N. Ramachandran, C.
Ramakrishnan, and V. Sasisekharan in 1963, the plot reveals that most of conformational space is forbidden due to steric clashes between backbone atoms. Allowed regions cluster into α-helix (~−57°, −47°), β-sheet (~−120°, +120°), and left-handed helix regions.
Glycine, with no side chain, has the most permissive Ramachandran plot (widest allowed regions). Proline, with its cyclic side chain, has the most restricted plot. Ramachandran analysis is a standard validation tool for protein structures determined by X-ray crystallography or NMR.
Key Facts
- Two-dimensional graph of backbone dihedral angles φ (phi) and ψ (psi) showing the sterically allowed conformations for amino acid residues in a peptide chain.
- Sasisekharan in 1963, the plot reveals that most of conformational space is forbidden due to steric clashes between backbone atoms.
- Allowed regions cluster into α-helix (~−57°, −47°), β-sheet (~−120°, +120°), and left-handed helix regions.
- Glycine, with no side chain, has the most permissive Ramachandran plot (widest allowed regions).
- Proline, with its cyclic side chain, has the most restricted plot.
- Ramachandran analysis is a standard validation tool for protein structures determined by X-ray crystallography or NMR.
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