Definition

1. Noun:
   • An essential amino acid: Phenylalanine is one of the amino acids that the human body cannot synthesize on its own and must obtain from the diet. It is a fundamental building block of proteins.
   • A biochemical precursor: In the human body, phenylalanine is normally converted into another amino acid called tyrosine, which is used to make important molecules.

Usage and Examples

• As a subject or object in a sentence:
  • Phenylalanine is listed in the ingredients of many diet sodas.
  • Proteins such as those found in milk contain phenylalanine.
  • People with the genetic disorder PKU cannot metabolize phenylalanine properly.

Advanced Usage and Context

• In nutritional science: The term is used to discuss dietary requirements, protein quality, and metabolic pathways.
  • The nutritional label indicates the presence of phenylalanine as a component of the protein aspartame.
• In medical contexts: It is central to discussions about the inherited metabolic disorder Phenylketonuria (PKU).
  • Newborns are screened for PKU to detect an inability to process phenylalanine.

Variants and Related Words

• Phenylketonuria (PKU) (n): A genetic disorder characterized by an inability to metabolize phenylalanine.
• Tyrosine (n): The amino acid into which phenylalanine is normally converted in the body.

Synonyms

• Essential amino acid: This is a category to which phenylalanine belongs. Other specific essential amino acids (e.g., leucine, valine) are not synonyms but are related in function.

Important Notes

• Not a phrasal verb or idiom: As a specific biochemical compound, phenylalanine is not used in phrasal verbs or idioms. Its usage is primarily scientific and technical.
• Spelling and identification: It is often abbreviated as "Phe" in scientific literature and on food labels for ingredients like the sweetener aspartame.

Noun

1. an essential amino acid found in proteins and needed for growth of children and for protein metabolism in children and adults; abundant in milk and eggs; it is normally converted to tyrosine in the human body