Comparison of Fluorometric and Chromatographic Methods of In Vitro Assay of Tryptophan Hydroxylase 2, the Key Enzyme of Serotonin Synthesis in the Brain

We present rapid and sensitive assay of tryptophan hydroxylase 2 enzyme activity based on the fluorescence of the complex of 5-hydroxytryptophan (5-HTP) with o-phthalic aldehyde. This method was compared with the standard method based on chromatographic isolation of 5-HTP followed by its quantification using an electrochemical detector. High sensitivity of the developed fluorometric method and similarity of the results obtained by fluorometric and chromatographic methods were demonstrated. The use of this rapid, cheap, and effective fluorometric method can simplify and facilitate measurements of tryptophan hydroxylase 2 activity and can make this assay available for a wide range of neurochemical and pharmacological laboratories.

Automated summary

We have developed a rapid and sensitive assay for measuring the activity of tryptophan hydroxylase 2 enzyme. This method is based on the fluorescence of the complex formed between 5-hydroxytryptophan (5-HTP) and o-phthalic aldehyde. It has been shown to be comparable to the standard chromatographic method in terms of accuracy and sensitivity. This new method offers a simplified and cost-effective solution for measuring tryptophan hydroxylase 2 activity, making it accessible to a wider range of research laboratories.