Protein Secondary Structure Section F
Alpha-HELIX
Alpha helix is held together by hydrogen bonds between the amide Hydrogen on the Nitrogen and another amide carbonyl oxygen of every 4th amino acid residue (approximately). These are intrachain H-bonds which along the same region of the backbone of the polypeptide or in other words within the same region of the amino acid sequence.
Figure 10. Simple Model of Alpha Helix with H-bonding Pattern.
The side chains of the amino acids project out from the core of the alpha helix. Water is excluded from the tight inner core of the alpha helix, which is very hydrophobic.
Figure 11. Side and Top Views of Alpha Helix illustrating the Position of the Side Chains.
©Wilbur H. Campbell, 1995; wcampbel@mtu.edu