Real-time monitoring of S-adenosyl-l-homocysteine hydrolase using a chemodosimetric fluorescence "turn-on" sensor

Although various methods have been used to measure the activity of S-adenosyl-l-homocysteine hydrolase (SAHase), most of them are rather complex, expensive, and not suitable for routine analysis. Herein, we describe simple fluorescence monitoring for SAHase activity using a synthetic probe that undergoes chemical binding selectively with l-homocysteine (Hcy), an enzyme metabolite from SAHase catalysis. The ring formation between the probe and Hcy during the enzyme catalysis is quantified by fluorescent emission from the binding adduct, which provides facile, real-time monitoring for the SAHase activity. The chemodosimetric reaction between the probe and Hcy is ∼100-fold faster than that for the enzyme catalysis so that it is successfully applicable in SAHase assay.