LIFESCI 3 Chapter Notes - Chapter 4.2: Electric Dipole Moment, Peptide, Partial Charge
Document Summary
Secondary structure: regularly repeating elements within a protein. Hydrogen bonds form between polar atoms in the backbone chain. Shield or neutralize charges and allow polar polypeptide to travel across the nonpolar interior of a protein. Main structure: helix (10-15 residues long) and conformation ( strands 3-10 residues long) Typical protein: alpha helix and one third beta conformation. Helix is a common form of protein secondary structure helix: Hydrogen on amide nitrogen forms h-bond with carbonyl oxygen of the fourth residue toward the n-terminus one helical turn. Hydrogen bonds point in the same direction electric dipole partial positive. Last 4 residues at either end are not fully h-bonded spread out dipole charges. Irregular conformations or more strained alpha helix with less favorable torsion angles. Consecutive stretches of amino acid residues with long or bulky r groups cannot approach each other close enough to form a tightly packed alpha helix. Polar side chains can h-bond to peptide backbones destabilize helix.
