International
Tables for
Crystallography
Volume F
Crystallography of biological macromolecules
Edited by M. G. Rossmann and E. Arnold

International Tables for Crystallography (2006). Vol. F. ch. 19.4, p. 441   | 1 | 2 |

Section 19.4.3.5. Nuclear spin contrast variation

D. M. Engelmana* and P. B. Mooreb

aDepartment of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA, and  bDepartments of Chemistry and Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
Correspondence e-mail:  don@paradigm.csb.yale.edu

19.4.3.5. Nuclear spin contrast variation

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When atomic nuclei of nonzero spin are placed in a magnetic field, the spins orient. If the temperature is near absolute zero, the orientation results in a polarization that is seen by polarized neutrons, resulting in polarization-dependent scattering. Since polarized neutron sources are available, and since biological materials are rich in hydrogen, Stuhrmann has proposed and tested a measurement based on the following idea (Stuhrmann & Nierhaus, 1996[link]). Consider a complex in which all of the hydrogen has been replaced by deuterium except in one subunit or ligand, and prepare a sample that can be frozen to T < 0.5 K, placed in a 2.5 T magnetic field and subjected to dynamic spin polarization. Scattering of polarized neutrons is measured twice, once with the hydrogen spins oriented, and once with the spins selectively depolarized using NMR saturation. The difference contains contributions from the hydrogenated region and a cross term between the region and the rest of the complex. Using a modelling approach, Stuhrmann and his colleagues have deduced a structure that locates transfer RNA molecules on a ribosome from polarized neutron data, revealing the promise of this approach (Stuhrmann & Nierhaus, 1996[link]).

References

First citation Stuhrmann, H. B. & Nierhaus, K. H. (1996). The determination of the in situ structure by nuclear spin contrast variation. Basic Life Sci. 64, 397–413.Google Scholar








































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