Definition of "phenylalanine" []

• An essential amino acid, C9H11NO2, that occurs as a constituent of many proteins and is normally converted to tyrosine in the human body. It is necessary for growth in infants and for nitrogen equilibrium in adults. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "PKU is described by scientists as an autosomal recessive genetic disease that is characterized by a deficiency in an enzyme called phenylalanine hydroxylase (PAH)."
• "It helps synthesize the body from the phenylalanine which is another type of amino acid."
• "- Amino acid deficiency - Amino acids such as phenylalanine, tyrosine and tryptophan provide the basis for the body's production of important neuro-transmitters in the body."