caa a22 4500 477136079 CHVBK 20180405111718.0 cr unu---uuuuu 170330e19971201xx s 000 0 eng 10.1023/A:1018348123074 doi (NATIONALLICENCE)springer-10.1023/A:1018348123074 Analysis of 1H chemical shifts in DNA: Assessment of the reliability of 1H chemical shift calculations for use in structure refinement [Elektronische Daten] [Sybren Wijmenga, Martijn Kruithof, Cees Hilbers] The reliability of 1H chemical shift calculations for DNA is assessed by comparing the experimentally and calculated chemical shifts of a reasonably large number of independently determined DNA structures. The calculated chemical shifts are based on semiempirical relations derived by Giessner-Prettre and Pullman [(1987) Q. Rev. Biophys., 20, 113-172]. The standard deviation between calculated and observed chemical shifts is found to be quite small, i.e. 0.17 ppm. This high accuracy, which is achieved without parameter adjustment, makes it possible to analyze the structural dependencies of chemical shifts in a reliable fashion. The conformation-dependent 1H chemical shift is mainly determined by the ring current effect and the local magnetic anisotropy, while the third possible effect, that of the electric field, is surprisingly small. It was further found that for a double helical environment, the chemical shift of the sugar protons, H2′ to H5′′, is mainly affected by the ring current and magnetic anisotropy of their own base. Consequently, the chemical shift of these sugar protons is determined by two factors, namely the type of base to which the sugar ring is attached, C, T, A, or G, and secondly by the χ-angle. In particular, the H2′ shift varies strongly with the χ-angle, and strong upfield H2′ shifts directly indicate that the χ-angle is in the syn domain. The H1′ shift is not only strongly affected by its own base, but also by its 3′-neighboring base. On the other hand, base protons, in particular H5 of cytosine and methyl protons of thymine, are affected mainly by the 5′-neighboring bases, although some effect (0.2 ppm) stems from the 3′-neighboring base. The H2 protons are mainly affected by the 3′-neighboring base. As a result of these findings a simple scheme is proposed for sequential assignment of resonances from B-helices based on chemical shifts. Kluwer Academic Publishers, 1997 Chemical shifts nationallicence Chemical shift calculation nationallicence DNA nationallicence RNA nationallicence Nucleic acids nationallicence Wijmenga Sybren Department of Medical Biochemistry and Biophysics, Umeå University, S-901 87, Umeå, Sweden aut Kruithof Martijn Nijmegen Son Research Center, Department of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut Hilbers Cees Nijmegen Son Research Center, Department of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut Journal of Biomolecular NMR Kluwer Academic Publishers 10/4(1997-12-01), 337-350 0925-2738 10:4<337 1997 10 10858 https://doi.org/10.1023/A:1018348123074 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1018348123074 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wijmenga Sybren Department of Medical Biochemistry and Biophysics, Umeå University, S-901 87, Umeå, Sweden aut NATIONALLICENCE 700 1- Kruithof Martijn Nijmegen Son Research Center, Department of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut NATIONALLICENCE 700 1- Hilbers Cees Nijmegen Son Research Center, Department of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut NATIONALLICENCE 773 0- Journal of Biomolecular NMR Kluwer Academic Publishers 10/4(1997-12-01), 337-350 0925-2738 10:4<337 1997 10 10858 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer