Basepairs involving Hoogsteen(H) edge of Adenine and Sugar(S) edge of Cytosine is shown. Highlighted examples are found from RNA crystal structures obtained from PDB.

Base pairs stabilized by N-H...N/O type hydrogen bonds only

Basepair

(type & Orientation)

*Frequency

Example

Hydrogen bonding atoms with their precursors

A:C H:S Cis

5

Optimized Model Structure

N3-O2 ... N6-N1

C6-O2' ... N7-C4

Base pairs stabilized by C-H...N/O interactions along with N-H...N/O hydrogen bonds

Basepair

(type & Orientation)

*Frequency

Example

Hydrogen bonding atoms with their precursors

A:C h:s Trans

0

Optimized Model Structure

C4-C8 ... O2-C4

C4-N7 ... O2'-C6

* 1st and 2nd numbers in Frequency column represent the numbers of occurences as base pairs and as base triplets, respectively.