Shapes of Protein-Macromolecule Complexes by Solid-State Nuclear Magnetic Resonance

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9316161 Schaefer Dr. Schaefer proposes new solid-state NMR experiments to determine the structures of big, non-crystallizeable complexes of proteins with macromolecules, including protein-protein cross-links in insect and plant cell walls, protein-oligosaccahride complexes, and protein-DNA complexes. The versatile rotational-echo double- resonance (REDOR) and transferred-echo double-resonance (TEDOR) analytical methods that he has developed in the last five years for the accurate determination of internuclear distances (and hence geometry and structure), and the new combined TEDOR-REDOR and TEDOR-TEDOR methods which he proposes to develop, are techniques that are directly applicable to the analysis of big complexes. The sensitivity of solid-state NMR for this kind of work already has been established in practical applications on big proteins. Dr. Schaefer now routinely performs long-range distance measurements on one umole of a 50-kD labeled protein complex embedded in an ionic glass, an amount of protein commonly used for conventional solution-state 1H multi-dimensional NMR. %%% The practical applications of REDOR solid-state NMR could lead both to new science and new biotechnology, the latter including the biorational design of pesticides, herbicides, and drugs. Dr. Schaefer plans to examine by NMR protein-protein cross-links in insect and plant cell walls, protein-oligosacahride complexes, and protein-DNA complexes. These complexes cannot be analyzed by other techniques because they are too big or are part of too heterogeneous a matrix. He also proposes to use atomic force microscopy (AFM) to characterize the global structure of some of the same protein complexes that we examine by NMR. Protein complexes anchored on the undulations of glassy polymer surfaces will be examined by non-perturbative "tapping-mode" AFM. The combination of NMR and AFM experiments on the same protein systems will provide an internal calibration (a self consistency check) and should lead to new structural insights. ***