Visualizing enzyme catalytic process using single-molecule techniques

The appearance of single-molecule techniques brings rapidly developed research on enzymology. The study of single-molecule enzymology excavates the individual behavior of single enzyme molecule hidden under the overall average. In this review, we summarize emerging developments of some single-molecule techniques, including total internal reflection fluorescence microscopy (TIRFM), confocal microscopy, fluorescence correlation spectroscopy (FCS) and magnetic tweezers or optical tweezers, in real time monitoring the catalytic process of single enzyme. A variety of enzymatic catalytic behaviors and corresponding mechanisms that differs from bulk experiment are discovered. Through analyzing the single molecule enzymatic kinetics coupled by the conformational changes of individual enzyme during catalysis, a deepened understanding of enzymatic reaction mechanism is obtained. Finally, this review provides a critical outlook on the further challenges of imaging and monitoring single enzymatic reaction in cellular environments.