BCHS 3304 Lecture Notes - Lecture 7: Peptide Bond, Alpha Helix, Hydrogen Bond
21 Sep 2016
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Document Summary
3-d protein structure: conformation= arrangement of atoms in space due to bonds/bond rotation. Most proteins have native conformation= stable conformation. Folded via: hydrophobic interactions, hydrogen bonds, ionic bonds, van der waals: noncovalent, weak interactions. 4 levels of protein structure: primary structure: linear, amino acid sequence. Very important to the structure and function of the protein. Residues connected thru peptide bonds: secondary structure: spatial alignment of residues. Ex: alpha helix, beta pleated sheets: tertiary structure: the 3 d structure. Reveals chemical mechanisms: quaternary structure: when multiple polypeptide chains assemble. Amide bond: there is resonance between the double bond of the c=o bond of the carbonyl of one residue, and the c-n peptide bond. This means the peptide bond is rigid. Peptide bond has 40% double bond character. C=o bond is longer than it would usually be, c-n bond is shorter than it would usually be.
