Question

13. a. What is Hoogsteen base pairing? (0.5 pt)

      b. Name three examples of Hoogsteen base pairs. (0.5 pt)

      c. What types of DNA structures can Hoogsteen base pairs induce? (0.5 pt)

Answer 1

13.

a.

Hoogsteen Base Pairing

In Hoogsteen base pairing there is variation in base pairing of nucleic acids. They show different geometries of base pairing between A- T and G-C bonds.

- The angle of Glycosidic bonds is larger in Hoogsteen base pairs

- In normal base pair the two C1 atoms are equidistant by 10.5 angstrom whereas in Hoogsteen base pairs the distance is about 8.65 angstroms.

b.

Watson crick base pairs are represented by - or .

Hoogsteen base pairs are represented by * or :

examples

T.A*A

C.G*G

T.A*T

C.

Quadruplex structures

Hoogsteen base pairs induce quadruplex structures. Quadruplex structures are secondary structures of single stranded DNA and RNA . G - Quadruplexes are formed as a result of hoogsteen base pairs.