Velikian, Irina, Acharya, Parag ORCID: https://orcid.org/0000-0003-2521-9968, Trifonova, Anna, Foldesi, Andras and Chattopadhyaya, Jyoti (2000) The RNA molecular wire: The pH-dependent change of the electronic character of adenin-9-yl is transmitted to drive the sugar and phosphate torsions in adenosine 3′, 5′-bisphosphate. Journal of Physical Organic Chemistry, 13 (5). pp. 300-305. ISSN 0894-3230 (Print), 1099-1395 (Online) (doi:10.1002/1099-1395(200005)13:5<300::AID-POC245>3.0.CO;2-W)

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Abstract

The change of the electronic character of adenin‐9‐yl in adenosine 3′,5′‐bisphosphate (EtpApMe, 1) in the neutral versus protonated form, in contrast to its abasic counterpart [Etp(apurinic)pMe, 2], is transmitted to modulate the sugar conformation by an interplay of stereoelectronic anomeric and gauche effects, which in turn dictate the phosphate conformation by tuning the 3′‐O—P—O(ester) anomeric effect. It was found that with the change of protonation ⇌ deprotonation equilibrium the electronic character of the aglycone changes, which is evident from the change of the pD‐dependent chemical shift of the aromatic protons (δH2 and δH8). This change in chemical shift (δH2, δH8) is linearly correlated with the pD‐dependent change of ΔG ° of the N ⇌ S pseudorotational equilibrium of the sugar moiety (from −2.8 kJ mol−1 at pD 7.9 to −1.7 kJ mol−1 at pD 1.0), as well as with the pD‐dependent change of ΔG ° of the two‐state ϵt ⇌ ϵ− equilibrium along the phosphate backbone (from −1.9 kJ mol−1 at pD 7.9 to −1.5 kJ mol−1 at pD 1.0). Finally, the pD‐dependent change of ΔG ° of the N ⇌ S pseudorotational equilibrium is also linearly correlated with that of the pD‐dependent ϵt ⇌ ϵ− equilibrium, thereby unequivocally showing that the pD‐dependent change of the electronic character of adenin‐9‐yl moiety (to its protonated form) is indeed propogated to drive the constituent sugar and phosphate backbone conformations in a concerted manner. The absence of such a correlation in the apurinic phosphodiester 2 implies that the change of the sugar conformation in 1 is independent of the electronic character of the phosphate. This tunable one‐way stereoelectronic transmission is modulated intramolecularly by a cascade of orbital overlaps basing on the donor and acceptor properties of various bonding, non‐bonding and antibonding orbitals, which cause a single‐stranded RNA to behave as molecular wire.

Item Type:	Article
Uncontrolled Keywords:	RNA, NMR conformation, protonation, anomeric and gauche effects
Subjects:	Q Science > Q Science (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Natural Resources Institute Faculty of Engineering & Science > Natural Resources Institute > Food & Markets Department
Last Modified:	08 Jul 2020 13:42
URI:	http://gala.gre.ac.uk/id/eprint/28733

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