Which of the following peptides is most likely to form an al

Which of the following peptides is most likely to form an alpha helix? Which is most likely to form a beta sheet? a. LVLAMWGFFK b. GKATYRPNNE c. AQIRVNTQIY

Solution

The alpha helix formation is determined largely by presence of glycine and proline which destabilize the alpha helix. Peptide 1 contains Glycine and peptide 2 contains proline and these peptides have least chances to form alpha helix. Peptide 3 has neither proline nor Glycine and therefore has highest probability to form alpha helix.

Beta-sheet formation is determined by amino acid propensities large aromatic residues (Tyr, Phe and Trp) and -branched amino acids (Thr, Val, Ile) are favored to be found in -strands in the middle of -sheets. Therefore the peptide 1 (LVLAMWGFFK) has highest of these amino acids, therefore has highest chances to form beta-sheets.