Prof. Williams’ main research interest is the biophysics of DNA-protein interactions. DNA is normally found as a double helix consisting of a sequence of base pairs, representing the genetic code. In order for this code to be read to create proteins (transcription and translation) or to make copies of the DNA (replication), the two strands of the double helix must be separated to expose the bases. The processes of replication and transcription are regulated by proteins that bind to DNA and alter the stability of the double helix. In his research Prof. Williams uses optical tweezers instruments to apply very small forces to single DNA molecules. Measurement of these forces allows him to determine the stability of the DNA double helix and the extent to which various DNA binding proteins alter the structure and stability of DNA. This approach provides unique insights into the function of these proteins in the cell.