1. An amino acid that is one of the 20 standard amino acids found in proteins; essential for growth and development, especially in infants.
Usage: biochemistry; often used in plural form 'histidines' when referring to multiple molecules or residues

Examples

• Histidine is classified as a semi-essential amino acid because the body can produce some but not always enough.
• The protein structure contains several histidine residues that help bind metal ions.
• Infants require dietary histidine because their bodies cannot synthesize it in sufficient quantities.
• Histidine plays an important role in immune function and tissue repair.
• The enzyme's active site includes a histidine residue that is critical for catalysis.
• Foods rich in histidine include chicken, beef, and cheese.
• Histidine can be converted into histamine, which is involved in allergic responses.