BCH210H1 Lecture Notes - Lecture 4: Peptide, Bond Length, Ramachandran Plot

• School: UTSG
• Department: Biochemistry
• Course: BCH210H1
• Professor: Stavroula Andreopoulos

Document Summary

Proteins are unbranched polymers of amino acids linked head to tail through the formation of covalent peptide bonds (amide linkage) Proteins are read from carboxyl group to amino group. Peptide bond formation release of water. Peptide backbone repeated sequence of -n-c -co- Only l-amino acids are found in proteins. 0. 145 nm) but longer than typical c=n bonds (0. 125 nm) Planar peptide bond two degrees of freedom per residue for the peptide chain rotation parameters phi ( ) and psi ( ) Ramachandran plot sterically possible values of psi, phi angles. Phi values of =180 and psi values of =0 have forbidden overlap of n-h hydrogens. Psi values of =180 and phi values of =0 have unfavourable overlap between carbonyl oxygens. Hydrogen bonds that make up secondary structures involve amide proton of one peptide group and carbonyl oxygen of another cooperative formation of structures. Nonpolar residues near helix termini can be exposed to solvent also solved by helix capping.