New Techniques for Purifying Large DNAs and Studying Their Properties and Packaging

Anyone who has ever handled an unsheared sample of high-molecular-weight DNA is familiar with the enormous mechanical and hydrodynamic challenge that such material presents both in vitro and in vivo. Eukaryotic cells use a hierarchy of protein packaging and organization to render their DNA more manageable. However, to study aspects of that DNA structure and organization, one must frequently remove most or all of this packaging and face the full obstacle presented by such large and relatively rigid molecules. Prokaryotic cells and viruses appear to use less-sophisticated DNA-packaging mechanisms, consistent with their smaller size. Very little is known about the details of this packaging.