Histidine Metabolism and Function. (1st October 2020)

• Record Type: Journal Article
• Authors: Brosnan, Margaret E; Brosnan, John T
• Is Part Of: Journal of nutrition. Volume 150(2020)Supplement 1
• Page Start: 2570S
• Page End: 2575S
• Publication Date: 2020-10-01
• Subjects: carnosine -- histamine -- histidase -- formiminoglutamate -- urocanate -- 3-methylhistidine; Nutrition -- Periodicals; Diet -- Periodicals; 613.205
• DOI: 10.1093/jn/nxaa079
• Languages: English
• ISSNs: 0022-3166

Abstract

ABSTRACT: Histidine is a dietary essential amino acid because it cannot be synthesized in humans. The WHO/FAO requirement for adults for histidine is 10 mg · kg body weight −1 · d −1 . Histidine is required for synthesis of proteins. It plays particularly important roles in the active site of enzymes, such as serine proteases (e.g., trypsin) where it is a member of the catalytic triad. Excess histidine may be converted to trans -urocanate by histidine ammonia lyase (histidase) in liver and skin. UV light in skin converts the trans form to cis -urocanate which plays an important protective role in skin. Liver is capable of complete catabolism of histidine by a pathway which requires folic acid for the last step, in which glutamate formiminotransferase converts the intermediate N-formiminoglutamate to glutamate, 5, 10 methenyl-tetrahydrofolate, and ammonia. Inborn errors have been recognized in all of the catabolic enzymes of histidine. Histidine is required as a precursor of carnosine in human muscle and parts of the brain where carnosine appears to play an important role as a buffer and antioxidant. It is synthesized in the tissue by carnosine synthase from histidine and β-alanine, at the expense of ATP hydrolysis. Histidine can be decarboxylated to histamine by histidine decarboxylase. This reaction occurs in the enterochromaffin-like cells of the stomach, in the mast cells of the immune system, and in various regions of the brain where histamine may serve as a neurotransmitter.