L-Phenylalanine Essay

The essential amino acid phenylalanine, with the molecular formula C9H11NO2, is abbreviated in the 3 letter form as Phe, or the single letter F, and is classified as a nonpolar amino acid due to the hydrophobic nature of the benzyl side chain (UPAC-IUBMB Joint Commission on Biochemical Nomenclature, 1983). The presence of the benzene ring determines that phenylalanine is an aromatic amino acid. Phenylalanine, being an essential amino acid, is needed by the body for many necessary biological functions, but cannot be produced by the body (Ehrlich, 2013). Thus, all phenylalanine taken in to the body must be ingested. Phenylalanine can be found in three different forms; D-phenylalanine, L-phenylalanine, and DL- phenylalanine. L-phenylalanine is an essential amino acid that is considered the natural form which is found in proteins. D-phenylalanine is a mirror image of L-phenylalanine that can only be made in the laboratory. DL-phenylalanine is simply a combination of the 2 forms at a 50%/50% mixture, making it a racemic compound (Ehrlich, 2013). Phenylalanine is a precursor for tyrosine, another amino acid that's needed to make proteins and brain chemicals which includes L-dopa, epinephrine, norepinephrine, and thyroid hormones (Ehrlich, 2013).
The lack of this enzyme leads to high levels of phenylalanine to accumulate due to phenylalanine being found in many naturally occurring and manufactured food products. Thus, if the enzyme is not present, this large consumption will cause toxic levels within the body. Typically if not treated before 3 weeks of age, these increased levels of phenylalanine can lead to irreversible intellectual disabilities such as mental retardation (Lyman,