ABSTRACT
This chapter discusses one of the most important classes of multi-functional organic molecules, amino acids. Amino acids are important biologically as constituents of peptides and proteins. The essential amino acids must be taken in by food since they cannot be made by the human body. The nine essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The initial product of the reaction with phenylacetaldehyde is the aminonitrile, 1-cyano-2-phenylethan-1-aminium. Saponification of the nitrile leads to the amino acid, phenylalanine. The amino group of glycine is protected as the benzyl carbamate and the carboxyl group of serine is protected as the ethyl ester. The N-terminal amino acid is converted to a N-phenyl-thiohydantoin by this procedure, cleaving only the terminal amino acid from the peptide and allowing easy identification of that amino acid. A peptide bond is an amide bond that connects amino acid residues in a peptide or in a protein.
