Transposase enzyme and DNA complex. Computer model showing the molecular structure of a TN5 transposase enzyme (purple) bound to the transposon end of a DNA molecule (green and pink). Transposons are sequences of DNA that can move, or transpose, themselves to new positions within the genome of a single cell. Transposase is an enzyme that binds to the ends of a transposon and catalyses the movement of the transposon to another part of the genome.