An efficient colorimetric high-throughput screening method for synthetic activity of tyrosine phenol-lyase

Tyrosine phenol-lyase (TPL) naturally catalyzes the reversible β-elimination of l-tyrosine to phenol, pyruvate and ammonium. With its reverse reaction (synthetic activity), l-tyrosine and its derivatives could be synthesized with high atom economy, which are widely used in pharmaceutical industries. In this study, a high-throughput screening method for synthetic activity of TPL was developed. One of the substrate, sodium pyruvate was found to react with salicylaldehyde under alkali condition, forming a yellow color compound. The concentration of sodium pyruvate can be quantified according to the absorbance of the colorimetric compound at wavelength of 465 nm and the activity of TPL could be screened according to the decrease of the absorbance. After optimization of the colorimetric reaction conditions, the established high-throughput screening method was successfully used for screening of TPL with enhanced activity for l-DOPA synthesis. The confirmed sensitivity and accuracy demonstrated the feasibility and application potential of this screening method.