PURCHASE OF A HIGH FIELD NMR SPECTROMETER

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Funds are requested for purchase of a nuclear magnetic resonance spectrometer that operates at he highest commercially available magnetic field. The very high field spectrometer will be located in the University of Iowa High Field NMR Facility. This existing centralized facility is modeled after BRS requirements for a shared usage resource. A Ph.D. level NMR specialist and B.S. level technician currently staff the Facility. A broad base of NMR usage exists at the University of Iowa, with some 30 research groups identified as active users of the existing 360 MHz spectrometer. These investigators will benefit from installation of a higher field spectrometer primarily in terms of the enhanced dispersion for proton spectroscopy and the improved sensitivity of heteronuclei. Detailed structural characterization of natural products provides the strongest rationale for an instrument with the highest possible field. Projects described here include structural elucidation of epidermal lipids, marine fungal natural products, cell surface oligosaccharides, heparin-derived oligosaccharides, alkaloid antibiotics, diterpenoids, antiviral nucleosides, and various anti-tumor agents. Three projects are concerned with determination of protein structure and enzyme active site characterization. Protein folding properties will be evaluated for small peptides derived from a ribonuclease analog and from thioredoxin. The active site chemistry of liver alcohol dehydrogenase will be probed through high resolution studies of histidine proton signals. Peroxidases and other hemoproteins will be examined in their paramagnetic states by proton spectroscopy and by heteronuclear methods in order to discern the involvement of heme region amino acids in peroxide activation. The very high field spectrometer will be utilized to evaluate field-dependent effects on molecular ordering and nuclear relaxation in paramagnetic systems.