Question

4. Dr. Kenneth Dill talked about amino acids, and the role they play in protein shape. Describe how the shape of proteins are formed in terms of amino acids. In other words, how does the sequence of amino acids dictate the final shape of the protein?

Answer 1

PROTEINS BONDS AND STRUCTURES H H H H2N - C со OH + H N- с - соон | R R2 АА. AA2 - CONH - Amide If amide bond is present in protein, it is known as PEPTIDE BOND → Covalent bond [on denaturation, this bond do not break (primary structure)] → Has double bond character Double bond is in 'trans' configuration In unsaturated fats, double bond is in 'cis configuration PROTEIN STRUCTURE 1° Structure 2° structure → Sequence of amino acids Obtained from folding of 10 structure - a Helix -B Sheets -B Turns Further folding fully folded structure 1 polypeptide chain нь 3° structure 4° struc MONOMERIC PROTEIN Those proteins which have only one moment, they donot have Quaternary structure O HELIX → Symmetrical helical structure → Secondary structure → mc helix found in the body → Right handed

AA not found in a-helix 1. Proline 2. Glycine 3. Tryptophan → 4. Aspartate or Glutamate 5. Valine Introduce 'kink' in a-helix Cause 'bend' in a helix Has bulky side chain 1° 3° 4 FEATURES Bond 20 H-bond Covalent Hydrophobic, Hydrogen, lonic S-S Hydrophobic, Hydrogen, lonic Present Absent Absent Present Functional Activity Denaturation Retained lost lost lost Detection Mass Spectrometry (best) and Edman's Technique 2° structure 3° Structure X ray crystallography (Best) - For Detecting 3 D structure of proteins or any other macromolecules (DNA) Non-crystallisable structure can't be detected 4° Structure NMR spectrometry - For non-crystallisable proteins