for Science 2Department of Molecular and Cellular Biology, Harvard University,

Single molecule measurements of DNA transport through a nanopore We examined the voltage-driven movement of single-stranded DNA molecules in a membrane channel or “nanopore”. Using single channel recording methods and a sta-tistical analysis of many single molecule events, we determined how voltage influences capture and translocation in the nanopore. We verified that the mean time between capture events follows a simple exponential distribution, whereas the translocation times follow a unique distribution that is partly Gaussian and partly exponential. Mea-surements of polymer sequence effects demonstrated that translocation duration is heavily influenced by specific or nonspecific purine-channel interactions. The single molecule approach we used revealed molecular interactions that can influence both capture rates and translocation velocities in a manner that enriches naive barrier cross-ing models