Alpha helix, illustration. This is a secondary structure formed from a protein's polypeptide chain of amino acids. This helical structure arises when the carbonyl group (a carbon atom double bonded to an oxygen atom) of one amino acid forms a hydrogen bond (white line) with the amino hydrogen atom of an amino acid four places down the chain. This alpha helix is composed of the amino acids tyrosine (pink), alanine (red), leucine (blue), glutamic acid (green), asparagine (orange), isoleucine (cyan), glutamine (yellow), arginine (red-orange), asparagine (orange) and (magenta).