A simple radioisotope assay for phenylalanine hydroxylase

✍ Scribed by Gordon Guroff; Amnon Abramowitz

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 478 KB
• Volume: 19
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(67)90245-x

✦ Synopsis

Recent studies in this laboratory (1, 2) have revealed new information about the mechanism of the phenylalanine hydroxylase reaction. Briefly, these experiments show that during hydroxylation the para substituent of the substrate, phenylalanine, migrates and appears on the meta position(s) of the product, tyrosine. In addition to providing insight into the chemistry of the reaction these observations have led to the development of a simple, rapid, and sensitive method for the assay of phenylalanine hydroxylase. The method is based on the use of p-tritio-L-phenylalanine as substrate. After the enzymic reaction the tyrosine which was formed is treated with N-iodosuccinimide to produce nz,m-diiodotyrosine (2)) and the amino acids are removed by absorption on Dowex 50. The tritium released by the combination of enzymic hydroxylation and iodination appears as tritiated water and can be used as a measure of the enzyme activity. The details of the method are described in this report. 'Guroff, G.. and Rhoads, C. .4., in preparation.