Which is the Hoogsteen base pairs?
A Hoogsteen base pair is a variation of base-pairing in nucleic acids such as the A•T pair. In this manner, two nucleobases, one on each strand, can be held together by hydrogen bonds in the major groove.
Where is Hoogsteen base pairing?
This type of base pairing is found in parallel DNA discussed in Chapter 7. Hoogsteen base pairs utilize the C6–N7 face of the purine for hydrogen bonding with the Watson–Crick (N3–C4) face of the pyrimidine (Hoogsteen, 1963).
What base pairs go together?
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.
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 causes Hoogsteen base pairing?
Hydrogen bonds in the Hoogsteen base pair are formed between the purine N7 to the pyrimidine N3 and either the adenine N6 to the thymine O6 or the guanine O4 to the cytidine N4 (4). Hoogsteen base pairs have been observed in several crystal structures of distorted double-stranded B-DNA.
What are base pairs made of?
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA.
Why is base pairing important?
Function. Complementary base pairing is important in DNA as it allows the base pairs to be arranged in the most energetically favourable way; it is essential in forming the helical structure of DNA. It is also important in replication as it allows semiconservative replication.
Which is a base pair in the Hoogsteen scheme?
Hoogsteen and reverse Hoogsteen base pairs. The A·U (or A·T) Hoogsteen pair is a well-known type of base pair (bp), named after the scientist who discovered it. As shown in the Figure below (left), in the Hoogsteen bp scheme, adenine uses its N7 (acceptor) and N6 (donor) atoms at the major groove edge to form two H-bonds with the N3 (donor)…
Are there any Hoogsteen base pairs in ca?
In some DNA sequences, especially CA and TA dinucleotides, Hoogsteen base pairs exist as transient entities that are present in thermal equilibrium with standard Watson–Crick base pairs. The detection of the transient species required the use of NMR techniques that have only recently been applied to macromolecules.
How are Hoogsteen base pairs used in proteins?
Chemical properties. Hoogsteen base pairs have been observed in protein–DNA complexes. Some proteins have evolved to recognize only one base-pair type, and use intermolecular interactions to shift the equilibrium between the two geometries. DNA has many features that allow its sequence-specific recognition by proteins.
What does Hoogsteen edge mean in RNA structure?
As a side note, the term Hoogsteen “edge” appears frequently in nowaday’s publications of RNA structures: in the Leontis-Westhof bp classification scheme, this term simply means the major groove edge in what would be a Watson-Crick bp geometry.