title: 2D exchange 31P NMR spectroscopy of bacteriophage M13 and tobacco mosaic virus.
abstract: Two-dimensional (2D) exchange 31P nuclear magnetic resonance spectroscopy is used to study the slow overall motion of the rod-shaped viruses M13 and tobacco mosaic virus in concentrated gels. Even for short mixing times, observed diagonal spectra differ remarkably from projection spectra and one-dimensional spectra. Our model readily explains this to be a consequence of the T2e anisotropy caused by slow overall rotation of the viruses about their length axis. 2D exchange spectra recorded for 30% (w/w) tobacco mosaic virus with mixing times < 1 s do not show any off-diagonal broadening, indicating that its overall motion occurs in the sub-Hz frequency range. In contrast, the exchange spectra obtained for 30% M13 show significant off-diagonal intensity for mixing times of 0.01 s and higher. A log-gaussian distribution around 25 Hz of overall diffusion coefficients mainly spread between 1 and 10(3) Hz faithfully reproduces the 2D exchange spectra of 30% M13 recorded at various mixing times in a consistent way. A small but notable change in diagonal spectra at increasing mixing time is not well accounted for by our model and is probably caused by 31P spin diffusion.
authors.affiliation: Department of Molecular Physics, Wageningen Agricultural University, The Netherlands.
authors.forename: P C
authors.initials: PC
authors.lastname: Magusin
authors.forename: M A
authors.initials: MA
authors.lastname: Hemminga
mesh_terms: D017104:Bacteriophage M13 / Q000737:chemistry*; D055592:Biophysical Phenomena; D001703:Biophysics; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008956:Models, Chemical; D009696:Nucleic Acids / Q000737:chemistry; D009698:Nucleoproteins / Q000737:chemistry; D010758:Phosphorus; D014027:Tobacco Mosaic Virus / Q000737:chemistry*; D014764:Viral Proteins / Q000737:chemistry
chemical_list: D009696:Nucleic Acids; D009698:Nucleoproteins; D014764:Viral Proteins; D010758:Phosphorus