Researchers from the Max Planck Institute for the Science of Light in Erlangen have developed a technique for directly observing how enzymes and other biomolecules go about their work, with potentially significant medical and scientific benefits. Using this technique, they have, for the first time with just light and without a marker, observed conformational changes in DNA polymerase, the enzyme responsible for replicating DNA. Because the technique can also be used to study how enzymes go about their work, it could help to identify new mechanisms for drug development.