title: Enzymatic cycling assay for phenylpyruvate.
abstract: Enzymatic cycling assays for the determination of L-phenylalanine and phenylpyruvate in deproteinized tissue extracts are described. Assay 1 couples glutamine transaminase K with L-phenylalanine dehydrogenase. Assay 2 combines phenylalanine dehydrogenase, L-amino acid oxidase, and catalase. In both assays, tyrosine and some other amino acids (or their alpha-keto acid analogs) can replace phenylalanine (or phenylpyruvate) to a small extent. Thus, if phenylalanine is to be measured a correction must be made for the nonspecificity of the reaction. By removing phenylalanine on a cation-exchange column it was possible to measure phenylpyruvate in tissue extracts. Concentrations of phenylpyruvate (mumol/kg) in normal rat liver, kidney, and brain were 2.1 +/- 1.1 (n = 8), 1.8 +/- 0.4 (n = 4), and 3.3 +/- 0.6 (n = 4), respectively.
authors.affiliation: Department of Biochemistry, Cornell University, Medical College, New York, New York 10021.
authors.forename: A J
authors.initials: AJ
authors.lastname: Cooper
authors.forename: L K
authors.initials: LK
authors.lastname: Leung
authors.forename: Y
authors.initials: Y
authors.lastname: Asano
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000818:Animals; D008297:Male; D008832:Microchemistry / Q000379:methods; D010649:Phenylalanine / Q000097:blood; D010667:Phenylpyruvic Acids / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity; D014018:Tissue Distribution; D000637:Transaminases / Q000378:metabolism
chemical_list: D010667:Phenylpyruvic Acids; D010649:Phenylalanine; D000594:Amino Acid Oxidoreductases; C022342:phenylalanine oxidase; D000637:Transaminases; C020656:glutamine-pyruvate aminotransferase; C031606:phenylpyruvic acid