ABSTRACT
A reassessment is made of some results for linear and circular DNA. The alternative side-by-side configuration is used in an analysis of situations where some doubt about current double helix based interpretations may exist. The following specific areas are considered: (i) certain linear DNA examples involving duplex interactions, (ii) nucleosome sequence data and (iii) the banding effect observed in gel electrophoresis studies of in vitro circular DNA.
ABSTRACT
Many studies indirectly indicate that the conformation of in vivo duplex DNA is the double helix. The most direct view, from the X-ray analysis of the nucleosome core particle, has also been interpreted in terms of the double helix structure. However, an alternative possibility exists; that the duplex adopts a metastable side-by-side conformation which readily converts to the double helix on removal of protein. Evidence for the existence of this conformation has been obtained from a reanalysis of the electron density map for the nucleosome particle.