Question

Which amino acids are not well suited for the alpha helical architecture and why?

Answer 1

α helix is secondary protein structure. Interchain hydrogen bonding and minimization of steric interferance between side chains. alpha helix is tightly packed, and at the end result of twisting formation is that the amino acid chain will form a rod. Methionine, alanine, leucine, glutamate, and lysine are tends to form an alpha helix. Amino acids with simple side chains, such as alanine, are very favorable for formation of alpha helices, whereas bulky (tryptophan) or cyclic (proline) amino acids tend to disrupt alpha helix. Amino acids whose R-groups are too large (tryptophan, tyrosine) or too small (glycine) destabilize α-helix. Proline also destabilizes α-helices because of its irregular geometry; its R-group bonds back to the nitrogen of the amide group, which causes steric hindrance.In short, Methionine, alanine, leucine, glutamate, and lysine ,all form  α helix, whereas proline and glycine have poor helix-forming propensities.