Table 4. Incidences of noncanonical base pairs in parallel and antiparallel strands as retrieved from the ndb_struct_na_base_pair.hbond_type_28 mmCIF token in 4447 DNA-containing structures.

All base-pair combinations are listed, including A–T and C–G pairs.

Base pair	A–A	A–C	A–G	A–T	C–C	C–G	C–T	G–G	G–T	T–T
Antiparallel	16	8	175	193	0	127	14	72	141	42
Parallel	34	0	0	1	115	0	0	153	0	3