title: Translational diffusion of macromolecular assemblies measured using transverse-relaxation-optimized pulsed field gradient NMR.
abstract: In structural biology, pulsed field gradient (PFG) NMR spectroscopy for the characterization of size and hydrodynamic parameters of macromolecular solutes has the advantage over other techniques that the measurements can be recorded with identical solution conditions as used for NMR structure determination or for crystallization trials. This paper describes two transverse-relaxation-optimized (TRO) (15)N-filtered PFG stimulated-echo (STE) experiments for studies of macromolecular translational diffusion in solution, (1)H-TRO-STE and (15)N-TRO-STE, which include CRINEPT and TROSY elements. Measurements with mixed micelles of the  Escherichia coli  outer membrane protein X (OmpX) and the detergent Fos-10 were used for a systematic comparison of (1)H-TRO-STE and (15)N-TRO-STE with conventional (15)N-filtered STE experimental schemes. The results provide an extended platform for evaluating the NMR experiments available for diffusion measurements in structural biology projects involving molecular particles with different size ranges. An initial application of the (15)N-TRO-STE experiment with very long diffusion delays showed that the tedradecamer structure of the 800 kDa  Thermus thermophilus  chaperonin GroEL is preserved in aqueous solution over the temperature range 25-60 °C.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Reto
authors.initials: R
authors.lastname: Horst
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Horwich
authors.forename: Kurt
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D018834:Chaperonin 60 / Q000737:chemistry*; D003902:Detergents / Q000737:chemistry; D004058:Diffusion; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006867:Hydrolases / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D016963:Thermus thermophilus / Q000737:chemistry
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018834:Chaperonin 60; D003902:Detergents; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; C482905:OmpX protein, E coli; D006867:Hydrolases