What is hoogsteen hydrogen bond?
Definition. A Hoogsteen Pair is a non-canonical/non-Watson-Crick hydrogen-bonded motif observed in nucleic acids. Two nucleosides from two different nucleic strands, or from distal regions of the same strand, can be held together by Hoogsteen base pairing.
Why does Hoogsteen base pairing occur?
Hoogsteen base pairs can also occur in regions of DNA that are highly distorted by bound protein. In the structure of TATA-binding protein (TBP) bound to DNA (3), a Hoogsteen base pair is observed in the region of DNA underwinding and intercalation by a phenylalanine side chain from TBP.
What is hoogsteen edge?
Like the purine, there is the Watson-Crick edge(WC) and the Sugar edge(S) but the third edge is referred to as the “C-H” edge(H) on the pyrimidine bases. This C-H edge is sometimes also referred to as the Hoogsteen edge for simplicity. The various edges for the purine and pyrimidine bases are shown in Figure 2.
What are hoogsteen positions?
A Hoogsteen base pair applies the N7 position of the purine base (as a hydrogen bond acceptor) and C6 amino group (as a donor), which bind the Watson–Crick (N3–C4) face of the pyrimidine base.
Can G pair with G in DNA?
In DNA, there are four nitrogenous base options: adenine (A), thymine (T), cytosine (C) and guanine (G). Each base can only bond with one other, A with T and C with G. This is called the complementary base pairing rule or Chargaff’s rule.
Can A ever pair with G?
The four bases of DNA each have their own size and shape, and are supposed to fit together in just the right way. Adenine (A) is always supposed to pair with thymine (T), and cytosine (C) is always supposed to pair with guanine (G). In fact, the G-T mutation is the single most common mutation in human DNA.
Can adenine pair with cytosine?
Attached to each sugar is one of four bases–adenine (A), cytosine (C), guanine (G), or thymine (T). The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.