Detection of tyrosine and monitoring tyrosinase activity using an enzyme cascade-triggered colorimetric reaction

• Published in: RSC advances Vol. 1; no. 5; pp. 29745 - 2975
• Main Authors: Chen, Huei-Yu, Yeh, Yi-Chun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 12.08.2020; The Royal Society of Chemistry
• Subjects: Biosensors; Cascade chemical reactions; Chemistry; Colorimetry; Dihydroxyphenylalanine; Dopamine; Enzymes; Metabolic disorders; Pretreatment; Tyrosinase; Tyrosine
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d0ra05581f

The aromatic amino acid tyrosine is an essential precursor for the synthesis of catecholamines, including l -DOPA, tyramine, and dopamine. A number of metabolic disorders have been linked to abnormal tyrosine levels in biological fluids. In this study, we developed an enzyme cascade-triggered colorimetric reaction for the detection of tyrosine, based on the formation of yellow pigment (betalamic acid) and red fluorometric betaxanthin. Tyrosinase converts tyrosine to l -DOPA, and DOPA-dioxygenase catalyzes oxidative cleavage of l -DOPA into betalamic acid. Response is linear for tyrosine from 5 to 100 M, and the detection limit (LOD) is 2.74 μM. The enzyme cascade reaction was applied to monitor tyrosinase activity and tyrosinase inhibition assays. Lastly, the performance of the proposed biosensor proved successful in the analysis of urine samples without the need for pre-treatment. We developed an enzyme cascade-triggered colorimetric reaction for the detection of tyrosine, based on the formation of yellow pigment (betalamic acid) and red fluorometric betaxanthin.