ABSTRACT
The right-handed Watson-Crick model of DNA was universally accepted as “The Secret of Life”. The discovery by Andy Wang of a left-handed helix in the first DNA crystallized was completely unexpected. This structure was called Z-DNA because of its “zig-zag” backbone and to distinguish it from the right-handed B-DNA. The structure was shown to be the same as that observed by Fritz Pohl and Thomas Joven when certain DNA polymers were exposed to salt concentrationsdramatically higher than t those found inside cells. The possibility that Z-DNA could exist under physiological conditions was enhanced by showing that chemical modifications of DNA lowered the salt requirement for Z-DNA formation. Larry Peck and James Wang also showed that the unwinding of DNA during RNA transcription could also release enough energy to drive Z-DNA formation. This chapter describes those events, tracing how the initial hype was followed by the rejection of the idea that Z-DNA had a biological role. I provide the background for this reversal of fortune.
