Photometric Determination of L-Tyrosine Based on the Catalytic Action of Tyrosinase Immobilized on Inner Membrane of Bamboo

It was proposed that tyrosinase was immobilized on the inner membrane taken from bamboo and activated by pentanedial to prepare a detection unit for photometric determination of L-tyrosine. The determination was based on the catalytic action of tyrosinase on the transformation of L-tyrosine to dopa-quinone which was in turn reacted with 3-methyl-2-benzothiazolinone hydrazone (MBTH) to give a chestnut colored additive product having its absorption maximum at 490 nm in a PBS of pH 7.0. Values of absorbance measured at this wavelength were found to keep linear relationship with concentration of L-tyrosine in the range from 5 to 200 μmol·L-1, with its detection limit (3S/N) of 2.5 μmol·L-1. The proposed method was applied to the determination of L-tyrosine in injections of compound amino acids the results obtained were in consistency with the labelled value.