Chapter 6, Problem 3E

Summary Introduction

To identify: The reason why α helix structure does not contain the following amino acids: Arg, Lys, Met, Phe, Trp, Tyr, and Val.

Concept introduction: α helix is one of the secondary structures of proteins. There are 3.6 residues per turn in the right-handed helical conformation. The peptide bond (C=O) of the nth residue points toward the peptide N-H group of the (n+4)th residue along the helical axis. This forms strong backbone hydrogen bonds.