Letters: April 2024
Readers discuss the handedness of DNA, celebrate the Explosives Act and reminisce about childhood experiments
Left handed might not be right
Rachel Brazil draws together many aspects of the biochemistry of Z-DNA in her feature article.
A commentary on the history of the putative left-handed form of DNA is also engaging. It is not universally accepted that the Z form is left handed. This handedness was deduced by Alexander Rich and his coworkers from fitting models they had built to their crystallographic diffraction patterns. It was not deduced from direct physical experimentation.
Many direct experimental results cast doubt upon that handedness. For example, several groups of crystallographers have reported that the right-handed B form, drawn into fibres, will transform itself into the Z form inside solid fibres. The mechanism and driving force necessary to effect a right-to-supposed-left helical transformation have never been explicit and have never been elaborated.