Biochemistry 2280A Lecture Notes - Lecture 3: Threonine, Glutamine, Lysine
22 Jun 2016
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Document Summary
Side groups give each amino acids their properties. Proteins and amino acids have directionality: may have same structure but different composition. H-bonds are strongest when three participating atoms are in a straight line. H-bond is sandwiched between to electron attracting atoms (usually o or n). Alpha helix: helical structure with precise dimensions: all c=o and n-h groups of peptide bond are involved in h-bonding, side chains point outward of the cylinder, 3. 6 residues for every turn, right-handed. Beta sheet: backbone h-bonds key to structure, extended structure involving interstrand h- bonds: composed of multiple beta-strands, anti-parallel strands, or parallel. In parallel beta-strands consecutive side chains are found on opposite faces of the strand. Loops are often exposed to the aqueous environment. Present at the end of secondary structural elements. Folding giving rise to shape from interactions between side chains, the backbone and backbone elements: stabilizes multiple weak molecular interactions. Interactions can be local or between distant regions.
