Question

The third strand of triple helix is paired in which scheme?

(a) Hoogsteen base pair scheme

(b) Intermolecular base pair scheme

(c) Intramolecular base pair scheme

(d) G-quartet scheme

This question was addressed to me by my school teacher while I was bunking the class.

My doubt stems from Structure of dsDNA topic in section Biomolecules and Catalysis of Life Sciences

Answer 1

The correct choice is (a) Hoogsteen base pair scheme

The explanation: Triple helix formed by three strands polypurine, polypyrimidine and the third strand which lay in the major groove of DNA and makes a hydrogen bond to duplex. The third strand is paired in hoogsteen base pairing scheme where the central strand is purine rich.