1. a) The following table shows the residues and corresponding phi (6) and psi (w) angles of a polypeptide chain. Critically review the given structure and draw the schematic 3D structure of the polypeptide and comment on its stability. [2] Residue Name Phi (6) in degree Psi (w) in Degree ASN-1 - -56 LEU-2 -44 -51 TYR-3 -66 -31 ILE-4 -65 -46 GLN-5 -65 -30 TRP-6 -73 -43 LEU-7 -65 -43 LYS-8 -60 -26 ASP-9 -78 -9 GLY-10 111 8 GLY-11 55 -124 PRO-12 -58 -29 SER-13 -82 19 SER-14 -124 13 GLY-15 68 25 ARG-16 -144 131 PRO-17 -70 160 PRO-18 -69 146 I PRO-19 -77 124 SER-20 -78 b) What percentage of amino acid residues of the above polypeptide sequence are within the disallowed region of the Ramachandran plot and comment on the stability of this structure. [3] c) If you look into thousands of cellular proteins, you find fewer small proteins with less than 50 residues. Give possible reasons for this observation. [1] d) DNase I is an enzyme that binds to the minor groove and cleaves DNA. Would you expect DNase I to cleave Z-DNA? Why? [1] e) DNA-protein dataset analysis revealed that in comparison to Lys, greater number of Arg residues are observed in the vicinity of DNA backbone. Give probable reason/s for the above fact. [1]