An amino acid which does not paicipate in alpha helix formation is
The stability of a helix arises primarily from hydrogen bonds formed between the oxygen of the peptide bond carbonyl and the hydrogen atom of the peptide bond nitrogen of the fouh residue down the polypeptide chain.Since the peptide bond nitrogen of proline lacks a hydrogen atom, it is incapable of forming a hydrogen bond with a carbonyl oxygen.Harper 30th edition pg: 38
Leucine
Glycine
Proline
Lysine
Structure and function of protein