• proton
  • The presence or absence of imino proton resonances, or of coupling between 15N atoms across a hydrogen bond, indicates the presence or absence of basepairing. (wikipedia.org)
  • The early method of structural determination of protein by NMR relied on proton-based homonuclear NMR spectroscopy in which the size of the protein that may be determined is limited to ~10 KDa. (wikipedia.org)
  • In 1977 Bodenhausen and Freeman showed how it was possible by observing spectrum of a heteronucleus (an atomic nucleus other than a proton) to achieve indirect detection of the proton resonance frequencies, and the correlations of chemical shifts between protons and heteronuclei. (wikipedia.org)
  • saturation transfer
  • His recent work has focused on developing new NMR methods (such as paramagnetic relaxation enhancement, dark state exchange saturation transfer spectroscopy and lifetime line broadening) to characterize the structure and dynamics of sparsely-populated states of macromolecules, which are important in macromolecular interactions but invisible to conventional structural and biophysical techniques. (wikipedia.org)
  • atoms
  • These properties are fundamentally the same as those used in the more familiar magnetic resonance imaging (MRI), but the molecular applications use a somewhat different approach, appropriate to the change of scale from millimeters (of interest to radiologists) to nanometers (bonded atoms are typically a fraction of a nanometer apart), a factor of a million. (wikipedia.org)
  • This type of spectroscopy determines the physical and chemical properties of atoms or the molecules in which they are contained. (wikipedia.org)
  • Russell H. Varian filed the "Method and means for correlating nuclear properties of atoms and magnetic fields", U.S. Patent 2,561,490 on July 24, 1951. (wikipedia.org)
  • Gradient
  • Since the resolution of the imaging technique depends on the magnitude of magnetic field gradient, many efforts are made to develop increased field strength, often using superconductors. (wikipedia.org)
  • The radio signal may be made to encode position information by varying the main magnetic field using gradient coils. (wikipedia.org)
  • The major components of an MRI scanner are: the main magnet, which polarizes the sample, the shim coils for correcting shifts in the homogeneity of the main magnetic field, the gradient system which is used to localize the MR signal and the RF system, which excites the sample and detects the resulting NMR signal. (wikipedia.org)
  • elucidation
  • He conducted preliminary investigations into the utilization of indirect covariance NMR spectroscopy as an alternative means of evaluating NMR data for structure characterization and Computer-Assisted Structure Elucidation. (wikipedia.org)
  • Historically, Wilkinson's catalyst has been a paradigm in catalytic studies leading to several advances in the field such as the implementation of some of the first heteronuclear magnetic resonance studies for its structural elucidation in solution (31P), parahydrogen-induced polarization spectroscopy to determine the nature of transient reactive species, or one of the first detailed kinetic investigation by Halpern to elucidate the mechanism. (wikipedia.org)
  • constants
  • Vicinal heteronuclear H-C-O-C coupling constants are used to study torsional angles along glycosidic bond between sugars or along exocyclic fragments, thus revealing a molecular conformation. (wikipedia.org)
  • Whereas, measurements of diffusion constants (diffusion ordered spectroscopy or DOSY) are done the sample stationary and spinning off, and flow cells can be used for online analysis of process flows. (wikipedia.org)
  • 1990
  • He also worked with Christophe Copéret on hybrid polarizing solids (HYPSOs) for Magnetic resonance imaging with 1990: National Latsis Prize awarded by the Latsis Foundation. (wikipedia.org)
  • spectrum
  • Accuracy of integration can be improved by inserting a chiral derivatizing agent with a nucleus other than hydrogen or carbon, then reading the heteronuclear NMR spectrum: for example fluorine-19 NMR or phosphorus-31 NMR. (wikipedia.org)
  • assignment
  • This limitation is due to the need to assign NMR signals from the large number of nuclei in the protein - in larger protein, the greater number of nuclei results in overcrowding of resonances, and the increasing size of the protein also broadens the signals, making resonance assignment difficult. (wikipedia.org)
  • protein
  • Protein nuclear magnetic resonance is performed on aqueous samples of highly purified protein. (wikipedia.org)
  • Protein NMR Spectroscopy. (wikipedia.org)
  • He is a member of the United States National Academy of Sciences, a NIH Distinguished Investigator, and the Chief of the Protein NMR Spectroscopy Section in the Laboratory of Chemical Physics of the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health. (wikipedia.org)
  • He is known for his foundational work in three-dimensional protein and nucleic acid structure determination by biomolecular NMR spectroscopy, for advancing experimental approaches to the study of large macromolecules and their complexes by NMR, and for developing NMR-based methods to study rare conformational states in protein-nucleic acid and protein-protein recognition. (wikipedia.org)
  • He has remained at the NIH ever since and is currently an NIH Distinguished Investigator and Chief of the Section on Protein NMR Spectroscopy at the NIH. (wikipedia.org)
  • placed in a magnetic field
  • When placed in a magnetic field, NMR active nuclei (such as 1H or 13C) absorb electromagnetic radiation at a frequency characteristic of the isotope. (wikipedia.org)
  • Rabi, Bloch, and Purcell observed that magnetic nuclei, like 1 H and 31 P , could absorb RF energy when placed in a magnetic field and when the RF was of a frequency specific to the identity of the nuclei. (wikipedia.org)
  • experiment
  • Nuclear magnetic resonance was first described and measured in molecular beams by Isidor Rabi in 1938, by extending the Stern-Gerlach experiment, and in 1944, Rabi was awarded the Nobel Prize in Physics for this work. (wikipedia.org)
  • In 1984 he published with Herbert Kogler and Richard R. Ernst a pivotal article in Journal of Magnetic Resonance where they described how to design phase cycles allowing the selection of specific coherence-transfer pathways in NMR pulse experiment. (wikipedia.org)
  • organic
  • Most frequently, NMR spectroscopy is used by chemists and biochemists to investigate the properties of organic molecules, although it is applicable to any kind of sample that contains nuclei possessing spin. (wikipedia.org)
  • peaks
  • The use of higher strength magnetic fields result in clear resolution of the peaks and is the standard in industry. (wikipedia.org)
  • As with NMR spectroscopy in general, good resolution requires a high signal-to-noise ratio, clear separation between peaks for each stereoisomer, and narrow line width for each peak. (wikipedia.org)
  • indirect
  • He has also explored the use of unsymmetrical indirect covariance NMR processing methods to define 13C-15N and 13C-13C heteronuclear connectivity networks. (wikipedia.org)
  • chemical shifts
  • Both use intense applied magnetic fields (H0) in order to achieve dispersion and very high stability to deliver spectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals). (wikipedia.org)
  • Bloch
  • The Purcell group at Harvard University and the Bloch group at Stanford University independently developed NMR spectroscopy in the late 1940s and early 1950s. (wikipedia.org)
  • Laboratory
  • He is professor of chemistry at the Department of Chemistry at the École Normale Supérieure (ENS) in Paris and professeur honoraire at the Laboratory of Biomolecular Magnetic Resonance of the École Polytechnique Fédérale de Lausanne (EPFL). (wikipedia.org)
  • methods
  • His ongoing research interests have centered on the development of new NMR methods for the characterization of impurities and degradants of pharmaceuticals focusing on the exploration of new NMR probe technologies for the characterization of extremely small samples using heteronuclear 2D-NMR methods. (wikipedia.org)
  • samples
  • The impact of NMR spectroscopy on the sciences has been substantial because of the range of information and the diversity of samples, including solutions and solids. (wikipedia.org)
  • During his time at Merck he has continued to explore the limits of detection for low level samples by heteronuclear 2D NMR using newly developed 1.7 mm Micro CryoProbe™ technology. (wikipedia.org)
  • large
  • Modern NMR spectrometers have a very strong, large and expensive liquid helium-cooled superconducting magnet, because resolution directly depends on magnetic field strength. (wikipedia.org)
  • known
  • It is useful for molecules of up to 100 nucleotides, and as of 2003, nearly half of all known RNA structures had been determined by NMR spectroscopy. (wikipedia.org)
  • field
  • The signal to noise ratio for 1H is about 300 fold greater than 15N at the same magnetic field. (wikipedia.org)
  • NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers. (wikipedia.org)
  • MRI scanners use strong magnetic fields, electric field gradients, and radio waves to generate images of the organs in the body. (wikipedia.org)
  • Pulses of radio waves excite the nuclear spin energy transition, and magnetic field gradients localize the signal in space. (wikipedia.org)
  • To perform a study, the person is positioned within an MRI scanner that forms a strong magnetic field around the area to be imaged. (wikipedia.org)
  • MRI requires a magnetic field that is both strong and uniform. (wikipedia.org)
  • Bodenhausen was one of the pioneers in the field of two-dimensional Fourier transform NMR spectroscopy. (wikipedia.org)