Nuclear magnetic resonance of the filamentous bacteriophage fd.

The filamentous bacteriophage fd and its major coat protein are being studied by nuclear magnetic resonance (NMR) spectroscopy. 31P NMR shows that the chemical shielding tensor of the DNA phosphates of fd in solution is only slightly reduced in magnitude by motional averaging, indicating that DNA-protein interactions substantially immobilize the DNA packaged in the virus. There is no evidence of chemical interactions between the DNA backbone and the coat protein, since experiments on solid virus show the 31P resonances to have the same principle elements of its chemical shielding tensor as DNA. 1H and 13C NMR spectra of fd virus in solution indicate that the coat proteins are held rigidly in the structure except for some aliphatic side chains that undergo relatively rapid rotations. The presence of limited mobility in the viral coat proteins is substantiated by finding large quadrupole splittings in 2H NMR of deuterium labeled virions. The structure of the coat protein in a lipid environment differs significantly from that found for the assembled virus. Data from 1H and 13C NMR chemical shifts, amide proton exchange rates, and 13C relaxation measurements show that the coat protein in sodium dodecyl sulfate micelles has a native folded structure that varies from that of a typical globular protein or the coat protein in the virus by having a partially flexible backbone and some rapidly rotating aromatic rings

A nuclear magnetic resonance study of Al-Mn quasicrystals and related materials

Nuclear magnetic resonance (NMR) results are presented for several aluminum alloy samples prepared using the melt-spinning technique including orthorhombic Al6Mn, Al-Mn quasicrystals both with and without doping with Si and Ru, and a T-phase alloy of A1 and Pt. With the exception of the orthorhombic material, all of the NMR spectra show a broad distribution of sites. No features unique to the quasicrystal phase are observed. For the orthorhombic material the quadrupole field parameters are found to be| vQ | = 1.0 ± 0.1 MHz and 77 = 0.4 + 0.1. © 1987, Materials Research Society. All rights reserved