P is for Proline. Create a protein by stringing this amino acid bead on a necklace. Proline is one of the two amino acids that do not follow along with the typical Ramachandran plot, along with glycine. Due to the ring formation connected to the Beta-carbon, the ? and ? angles about the peptide bond have less allowable degrees of rotation. Proline is the only amino acid that does not form a blue/purple color when developed by spraying with ninhydrin for uses in chromatography. Proline, instead, produces an orange/yellow color.