B-DNA is the Watson–Crick form of the double helix that
most people are familiar with (Figure 1). It was first
identified in fibres at 92% relative humidity. Several
sequences crystallized to high resolution have been found
to adopt the B-DNA conformation. Although on average
the conformation of B-DNA is the same in crystals as in
solution, the local structure is strongly dependent on its
local sequence. Table 1 lists some of the different structural
parameters for B-DNA as a function of dinucleotide
sequence. The table also shows the average parameters,
which are very close to the values obtained in fibre
diffraction studies. Of the three families of DNA helices,
B-DNA is the most common, and also the most variable in
structure.