Abstract
In many NMR experiments, only polarisation of a limited sub-set of all protons is converted into observable coherence. As recently shown by the “longitudinal” TROSY implementation (Pervushin et al. (2002) J. Am. Chem. Soc., 124, 12898–12902) and SOFAST-HMQC (Schanda and Brutscher (2005) J. Am. Chem. Soc., 127, 8014–8015), recovery of unused polarisation can be used indirectly and unspecifically to cool the proton lattice and, thus, accelerate re-equilibration for the selected proton subset. Here we illustrate transfer of this principle to HSQC-based multi-dimensional out-and-back experiments that exploit only polarisation of 15N-bound protons. The presented modifications to the pulse sequences can be implemented broadly and easily, extending standard flip-back of water polarisation to a much larger pool of protons that may comprise all non−15N-bound protons. The underlying orthogonal separation of HN polarisation (selected by the main transfer path) from unused Hu polarisation (flipped-back on the recovery path) is thereby achieved through positive or negative selection by J-coupling, or using band-selective pulses. In practice, Hu polarisation recovery degrades mostly through cumulative pulse imperfections and transverse relaxation; we present, however, strategies to substantially minimise such losses particularly during interim proton decoupling. Depending on the protein’s relaxation properties and the extended flip-back scheme employed, we recovered up to 60% Hu equilibrium polarisation. The concomitant cooling of the proton lattice afforded substantial gains of more than 40%, relative to the water-only flip-back version, in the fast pulsing regime with re-equilibration delays τ much shorter than optimal (τopt = 1.25 · T1(HN)). These would be typically employed if resolution requirements dominate the total measurement time. Contrarily, if sensitivity is limiting and optimal interscan delays τopt can be set (optimal pulsing regime), the best of the presented flip-back schemes may still afford up to ca. 10% absolute sensitivity enhancement.
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Abbreviations
- bsfb:
-
band-selective flip-back
- cpd:
-
continuous pulsing decoupling
- efb:
-
extended flip-back
- Hu:
-
unselected proton magnetisation
- HCfb:
-
HCflip-back
- ufb:
-
universal flip-back
- wfb:
-
water flip-back
References
A. Abragam (1961) NoChapterTitle R.K. Adair R.J. Elliott W.C. Marshall D.H. Wilkinson (Eds) Principles of Nuclear Magnetism. The International Series of Monographs on Physics Clarendon Press Oxford/UK
L. Braunschweiler R.R. Ernst (1983) J. Magn. Reson. 53 521–528 Occurrence Handle1:CAS:528:DyaL3sXks1eju7c%3D
L. Emsley G. Bodenhausen (1992) J. Magn. Reson. 97 135–148 Occurrence Handle1:CAS:528:DyaK38XhvVKgsLc%3D
R.R. Ernst G. Bodenhausen A. Wokaun (1987) NoChapterTitle J.S. Rowlinson (Eds) Principles of Nuclear Magnetic Resonance in One and Two Dimensions. The International Series of Monographs on Chemistry NumberInSeries14 Clarendon Press Oxford/UK
J. Furrer F. Kramer J.P. Marino S.J. Glaser B. Luy (2004) J. Magn. Reson. 166 39–46 Occurrence Handle10.1016/j.jmr.2003.09.013 Occurrence Handle1:CAS:528:DC%2BD3sXpvVWltbs%3D
H. Geen R. Freeman (1991) J. Magn. Reson. 93 93–141
T. Gullion D. Baker M.S. Conradi (1990) J. Magn. Reson. 89 479–484 Occurrence Handle1:CAS:528:DyaK3MXhs1ejug%3D%3D
K. Hallenga G.M. Lippens (1995) J. Biomol. NMR 5 59–66 Occurrence Handle1:CAS:528:DyaK2MXjtlyju70%3D
S. Hiller G. Wider T. Etezady-Esfarjani R. Horst K. Wüthrich (2005) J. Biomol. NMR 32 61–70 Occurrence Handle10.1007/s10858-005-3070-8 Occurrence Handle1:CAS:528:DC%2BD2MXmsVOqsrY%3D
L.E. Kay G.Y. Xu T. Yamazaki (1994) J. Magn. Reson. A109 129–133
M.H. Levitt (1982) J. Magn. Reson. 48 234–264 Occurrence Handle1:CAS:528:DyaL38XktlamsL4%3D
S. Ludvigsen H. Shen M. Kjaer J.C. Madsen F.M. Poulsen (1991) J. Mol. Biol. 222 621–635 Occurrence Handle10.1016/0022-2836(91)90500-6 Occurrence Handle1:CAS:528:DyaK38Xht1ektLY%3D
S. Meiboom D. Gill (1958) Rev. Sci. Instrum. 29 688–691 Occurrence Handle10.1063/1.1716296 Occurrence Handle1:CAS:528:DyaF3cXosFWitQ%3D%3D
K. Pervushin B. Vögeli A. Eletsky (2002) J. Am. Chem. Soc. 124 12898–12902 Occurrence Handle10.1021/ja027149q Occurrence Handle1:CAS:528:DC%2BD38XnsVeksLw%3D
R. Riek J. Fiaux E.B. Bertelsen A.L. Horwich K. Wüthrich (2002) J. Am. Chem. Soc. 124 12144–12153 Occurrence Handle10.1021/ja026763z Occurrence Handle1:CAS:528:DC%2BD38XntFSis7g%3D
M. Sattler J. Schleucher C. Griesinger (1999) Progr. NMR Spectr. 34 93–158 Occurrence Handle1:CAS:528:DyaK1MXisF2jsbk%3D
P. Schanda B. Brutscher (2005) J. Am. Chem. Soc. 127 8014–8015 Occurrence Handle10.1021/ja051306e Occurrence Handle1:CAS:528:DC%2BD2MXktFCgtrc%3D
A.J. Shaka P.B. Barker R. Freeman (1985) J. Magn. Reson. 64 547–552 Occurrence Handle1:CAS:528:DyaL2MXmt1KjtLs%3D
A.J. Shaka J. Keeler T. Frenkiel R. Freeman (1983) J. Magn. Reson. 52 335–338 Occurrence Handle1:CAS:528:DyaL3sXhvFSntrk%3D
A.J. Shaka C.J. Lee A. Pines (1988) J. Magn. Reson. 77 274–293
T.E. Skinner T.O. Reiss B. Luy N. Khaneja S.J. Glaser (2004) J. Magn. Reson. 167 68–74 Occurrence Handle10.1016/j.jmr.2003.12.001 Occurrence Handle1:CAS:528:DC%2BD2cXhsFeltrw%3D
V. Sklenar (1995) J. Magn. Reson. A114 132–135
V. Sklenar M. Piotto R. Leppik V. Saudek (1993) J. Magn. Reson. A102 241–245
M. Smith H. Hu A.J. Shaka (2001) J. Magn. Reson. 151 269–283 Occurrence Handle10.1006/jmre.2001.2364 Occurrence Handle1:CAS:528:DC%2BD3MXmsVGisLc%3D
R. Tycko A. Pines (1984) Chem. Phys. Lett. 111 462–467 Occurrence Handle10.1016/0009-2614(84)85541-4 Occurrence Handle1:CAS:528:DyaL2cXmtl2iurs%3D
M. Zweckstetter T.A. Holak (1999) J. Biomol. NMR 15 331–334 Occurrence Handle10.1023/A:1008360013567 Occurrence Handle1:CAS:528:DC%2BD3cXhtFChsrY%3D
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Diercks, T., Daniels, M. & Kaptein, R. Extended Flip-back Schemes for Sensitivity Enhancement in Multidimensional HSQC-type Out-and-back Experiments. J Biomol NMR 33, 243–259 (2005). https://doi.org/10.1007/s10858-005-3868-4
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DOI: https://doi.org/10.1007/s10858-005-3868-4