HoogsteenHBindungen

Hoogsteen base pairing is a form of nucleic acid base pairing that differs from the more common Watson-Crick pairing. In Hoogsteen pairing, a purine base (adenine or guanine) interacts with a pyrimidine base (cytosine or thymine) using a different set of hydrogen bond donors and acceptors. Specifically, it involves the N7 atom of the purine and the N3 atom of the pyrimidine, as opposed to the N1 and N3 of purines and N1 and N3 of pyrimidines in Watson-Crick pairing. This alternative arrangement results in a distinct geometry of the base pair.

Hoogsteen base pairing plays a crucial role in various biological processes. One significant example is in the formation of G-quadruplexes, which are four-stranded DNA structures stabilized by Hoogsteen hydrogen bonds between guanine bases. These structures are implicated in telomere maintenance and gene regulation. Hoogsteen pairing is also observed in some forms of RNA secondary and tertiary structures, as well as in DNA repair mechanisms. The ability of bases to form these alternative pairings contributes to the structural versatility and functional complexity of nucleic acids. Understanding Hoogsteen base pairing is essential for comprehending the intricate molecular mechanisms that govern genetic information storage and processing.