Enzymatic Determination of L-Phenylalanine and L-Tyrosine

Abstract

An enzymatic method for the determination of phenylalanine and tyrosine has been described. This method is based on the formation of cinnamic acid from phenylalanine or the formation of p-coumaric acid from tyrosine by phenylalanine ammonialyase of Rhodotorula. Cinnamic acid and p-coumaric acid, which are formed in stoichiometric amounts, are determined spectrophotometrically. Other amino acids and D-isomers of phenylalanine and tyrosine have no effect on this determination.