Tautomeric shifts in DNA bases
and rare enol
forms of T & G [left and
right] differ by a spontaneous proton
shift between the adjacent O
and N molecules. Note that the
formula does not change, only the configuration of
bonds among atoms:
and enol forms are
therefore tautomers of each other.
standard amino and rare imino
forms of A [middle] also differ by a
spontaneous tautomeric shift between the the adjacent N molecules. Standard amino
and rare imino
forms of C [not shown] differ in
the same way.