Measurements of water proton NMR spin-lattice relaxation time in the rotating frame (T1p) for studying motions in solutions of giant macro-molecules and supramolecular particles (T2 virus).

Spin-spin relaxation time (T2), spin-lattice relaxation time (T1), and spin-lattice relaxation time in the rotating frame (T1p) of water protons in solutions of bacteriophage T2 were studied by pulsed nuclear magnetic resonance. The frequency dependence of the measurements exhibits a dispersion implying existence of a fraction of water molecules in solution with a correlation time distribution centered at approximately 10(-5) sec which is strongly influenced by the reorientational motions of virus particles. Experiments were carried out with two forms of bacteriophage T2 existing at pH 5.4 and 7.8 respectively. The different structures of the virus at these two pH values are reflected in the NMR relaxation behavior of water protons.