User:Tilman Schirmer/Sandbox 99
From Proteopedia
Peptide bond
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The <scene='User:Tilman_Schirmer/Sandbox_99/Diala/20'/>peptide bond </scene> formation is a condensation reaction between the carboxyl group of the amino acid ni and the amino group of the amino acid ni+1.
The is defined by the four atoms φ = C - N - Cα - C (yellow: bond between N - Cα).
The is defined by the four atoms ψ = N - Cα - C - N (green: bond between Cα - C).
The is defined by the four atoms ω = Cα - C - N - Cα (orange: bond between C - N).
The peptide bond is a resonance structure between two limiting states. Therefore the N-C bond has a partial double bond character and the atoms/groups Cα, HN, C, C=O are within one plane. Peptide bonds are usually in trans conformation (ω torsion angle= 180°) due to sterical hindrance between Cβ and the C=O carbonyl. Cis conformation can occur only for the peptide bonds preceding Pro or Gly residue, where no Cβ is interfering.
