Nuclear magnetic resonance study of the molecular conformation of .beta.-pseudouridine in aqueous solution

Abstract

A computer analysis of the entire 100-MHz nmr spectrum of the modified nucleoside /3-pseudouridine, ß-, in aqueous solution is reported. The analysis was confirmed by spin-tickling and spin-decoupling experiments. The results are used to determine a model for the conformation of the nucleoside. An equilibrium between various puckered ring conformations is proposed. The populations of the various rotamers about the Cv-Cs-bond are evaluated; a preference for the gauche-gauche rotamer is indicated. Comparison with the available data for uridine indicates that the two compounds have almost identical ribose conformations, and that the uracil moiety in (47) R.

Proton Magnetic Resonance Studies of 2′-Deoxythymidine, its 3′- and 5′-Monophosphates and 2′-Deoxythymidylyl-(3′, 5′)-2′ -deoxythymidine in Aqueous Solution

“…This is so because of the cis (gauche) relationship of H,,-H,,, and Hz,-H3, pairs in all possible puckered modes of a deoxyribose ring and because of the inverse relationship between J,,,, and J,,,,, a consequence of which is the fact that changes in the 2'-endo t-. 3'-endo blend produce essentially equal but opposite effects on the individual couplings (14,17,43,45). Thus differences in the compared values should exhibit reasonably welldefined trends in view of the structural differences between molecules compared (i.e.…”

A Nuclear Magnetic Resonance Study of Nucleoside Conformation in Solution. The Effect of Structure and Conformation on the Magnetic Nonequivalence of the 5′-Methylene Hydrogens

“…In this work no attempt is made a t any indepth analysis of their relative contributions; our purpose is simply to determine whether the magnetic nonequivalence observed for the diastereotopic 5'-hydrogens of a series of nucleosides and nucleotides can be related to their structural and conformational properties. Recently we reported (13)(14)(15) the complete analyses of the p.m.r. spectrum of P-pseudouridine (Q), a-pseudouridine (a$), and uridine (U) ( are correlated with the sum of the 4'-5' vicinal H-H coupling constants and therefore must be directly related t o the conformational preferences about the exocyclic C,.-C,, bond.…”

Conformation about the glycosidic bond: Ribose‐nicotinamide of NAD+ bound to some dehydrogenases

“…The conformation about the glycosidic bond of 2-Me and 6-Me NAD ÷ may be safely deduced from the results of studies on the conformation of cytidine [14] and uridine [14][15][16] and their C-6 methyl analogues [14,17,18]. Cytidine and uridine exist in the anti conformation in solution [14][15][16] whereas 6-methylcytidine and 6-methyluridine are syn under the same conditions [14,17,18]. In the crystalline state, cytidine isanti [19] and 6-methyluridine syn [20] (same results as in solution).…”