Isotope selective activation: a new insight into the catalytic activity of urease

摘要

Urease, a metalloenzyme, requires carbon dioxide (CO2) for its activation. But, whether this activation is isotope-specific to (CO2)-C-12 or (CO2)-C-13, is not yet known and even the potential role of CO2 in the enzymatic activity of urease is poorly understood. Here, we provide direct experimental evidence that the catalytic activity of urease exhibits a unique isotope-specific response where the (CO2)-C-12 isotope is strongly preferred over the 1(3C)O(2) isotope during its catalytic activation. Moreover, this isotope-selective activation depends on different isotopic fractionations (C-12: C-13) of the reaction-environment as well as the substrate urea (C-13-urea and C-12-urea), where the (CO2)-C-12 isotope in the reaction medium essentially facilitates the hydrolysis of C-13-enriched urea. This deepens our understanding of the isotope-specific urease activation and its potential role in hydrolytic reaction. Our findings thus may offer novel opportunities for a better fundamental understanding of isotope-specificity in chemical reactions involving metalloenzymes.