Wyss Institute at Harvard University 1 article published in JoVE Biochemistry Single-Molecule Dwell-Time Analysis of Restriction Endonuclease-Mediated DNA Cleavage Candice M. Etson1,2, Petar Todorov1, Nooshin Shatery Nejad2, Nirmala Shrestha2, David R. Walt1,3 1Department of Chemistry, Tufts University, 2Department of Physics, Wesleyan University, 3Wyss Institute at Harvard University Using quantum-dot-labeled DNA and total internal reflection fluorescence microscopy, we can investigate the reaction mechanism of restriction endonucleases while using unlabeled protein. This single-molecule technique allows for massively multiplexed observation of individual protein-DNA interactions, and data can be pooled to generate well-populated dwell-time distributions.