Map Sapling Learning A small generic section of the primary structure of an a he
ID: 282281 • Letter: M
Question
Map Sapling Learning A small generic section of the primary structure of an a helix is given below. - amino acid-amino acid2-amino acids-amino acid4-amino acids-amino acids-amino acid?- (a) Which amino acid residue's backbone forms a hydrogen bond with the backbone of the second (2nd) residue? Choose the correct residue from the drop-down menu. amino acid Select answer (b) Which of the following peptide segments is most likely to be part of a stable a helix at physiological pH? yrTrp-Phe-Val-lle- O -Pro-Leu-Thr-Pro-Trp- O -Lys-Lys-Ala-Arg-Ser- O -Gly-Arg-Lys-His-Gly- O-Glu-Leu-Ala-Lys-Phe- O -Gly-Gly-Gly-Ala-Gly- O -Glu- Glu-Glu-Glu-Glu- Previous O Check Answer Next Exit HintExplanation / Answer
A- In Alpha Helix First amino acid residue form H-bond with the Fifth amino acid, second from H-bond with the sixth residue or in other words nth amino acid from H-bond with N+4 the residue.
So the answer will be second amino acid will form H-bond with sixth amino acid residue.
B- In the case of an alpha-helix all the polar residues are on one side and all the non-polar residues are on the other side of the residue so that the alpha-helix is stabilized.
Proline is known to be a breaker of alpha-helix. So it is rarely found in alpha helix. At physiological pH, the net charge on the alpha-helix should be zero.
Chain 6- Gly-Gly-Gly-Ala-Gly will be most likely to form alpha helix at physiological pH