Effect of Cadmium Ion on alpha-Glucosidase: An Inhibition Kinetics and Molecular Dynamics Simulation Integration Study

Tao Luo, Jinhyuk Lee, Zhi-Rong Lü, Hang Mu, Li-Mei Yue, Yong-Doo Park, Zhuo-Ming Ye

α-Glucosidase is a critical metabolic enzyme that produces glucose molecules by catalyzing carbohydrates. The aim of this study is to elucidate biological toxicity of Cd(2+) based on α-glucosidase activity and conformational changes. We studied Cd(2+)-mediated inactivation as well as conformational modulation of α-glucosidase by using kinetics coupled with simulation of molecular dynamics. The enzyme was significantly inactivated by Cd(2+) in a reversibly binding behavior, and Cd(2+) binding induced a non-competitive type of inhibition reaction (the K i was calculated as 0.3863 ± 0.033 mM). Cd(2+) also modulated regional denaturation of the active site pocket as well as overall partial tertiary structural change. In computational simulations using molecular dynamics, simulated introduction of Cd(2+) induced in a depletion of secondary structure by docking Cd(2+) near the saccharides degradation at the active site, suggesting that Cd(2+) modulating enzyme denaturation. The present study elucidated that the binding of Cd(2+) triggers conformational changes of α-glucosidase as well as inactivates catalytic function, and thus suggests an explanation of the deleterious effects of Cd(2+) on α-glucosidase.