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 NMR, Synchrotrons & Crystallography glossary & taxonomy
Evolving Terminologies for Emerging Technologies
Comments? Questions? Revisions? 
Mary Chitty MSLS
Last revised January 07, 2020

Technologies term index  Related glossaries include Protein Structures,    Protein informatics     Proteomics

Includes COSY and NOESY
3D NMR: See multidimensional NMR
4D NMR: See multidimensional NMR

beamline: In particle physics, a beamline is the line along which a beam of particles travels through, or when projected from, a particle accelerator. It may refer to the line of travel within an actual accelerator, and to the equipment that maintains that beam in a storage ring or accelerates it in a linear accelerator. It may also refer to a beam of X-rays projected to stations for doing crystallography  Beamline, Wikipedia, accessed Oct. 3, 2005    Related terms: synchrotrons, Industrial Macromolecular Crystallography Association IMCA 

bicelles: in certain regimes so-called bilayered mixed micelles or “bicelles” are formed. In the simplest case, they can be described as microscopic disks where a bilayer patch is encircled by a “rim” of detergent molecules. Bicelles represent a new instance of lipid morphology and are extensively applicable to structural studies of lipid membranes and protein structure.1 Dürr UHN, Gildenberg M, Ramamoorthy A. The Magic of Bicelles Lights Up Membrane Protein Structure. Chemical Reviews. 2012;112(11):6054-6074. doi:10.1021/cr300061w.

13C : Carbon isotopes used in NMR labeling.

COSY: Correlated Spectroscopy, 2D NMR.

chemical shift: The variation of the resonance frequency of a nucleus in nuclear magnetic resonance (NMR) spectroscopy in consequence of its magnetic environment. The chemical shift of a nucleus, is expressed in ppm by its frequency, cpd, relative to a standard, ref, and defined as = 106(cpd - ref)/o  where o is the operating frequency of the spectrometer. For 1H and 13C NMR the reference signal is usually that of tetramethylsilane (SiMe4). Other references are used in the older literature and in other solvents, such as D2O.  If a resonance signal occurs at lower frequency or higher applied field than an arbitrarily selected reference signal, it is said to be upfield, and if resonance occurs at higher frequency or lower applied field, the signal is downfield. Resonance lines upfield from SiMe4 have positive, and resonance lines downfield from SiMe4 have negative -values. IUPAC  Physical Organic Chemistry

chemical shift anisotropy CSA: A “relaxation” property. 

comparative spectral analysis CoSA: SEE under Quantitative 13C NMR Spectrometric Data- Activity Relationships Modeling QSDAR
comparative structural connectivity spectra analysis CoSCSA: SEE under Quantitative 13C NMR Spectrometric Data- Activity Relationships Modeling QSDAR
comparative structurally assigned spectral analysis CoSASA: SEE under Quantitative 13C NMR Spectrometric Data- Activity Relationships Modeling QSDAR 

cryogenic probe: One of the engineering challenges has been to cool the detection circuitry to these very low temperatures while maintaining the sample itself at ambient temperatures.  The first generation of these cryoprobes provides a factor of three improvement in signal- to- noise ratio, which means about a factor of nine or ten reduction in data collection time. Soon we will be able to combine the cryoprobes with the NOESY data collection and residual dipolar coupling to determine complete high- quality protein structures much faster. Related terms: cryoprobe, microcryoprobes, triple resonance cryoprobes.

crystallography: the experimental science of determining the arrangement of atoms in crystalline solids (see crystal structure). The word "crystallography" derives from the Greek words crystallon "cold drop, frozen drop", with its meaning extending to all solids with some degree of transparency, and graphein "to write". .. X-ray crystallography is used to determine the structure of large biomolecules such as proteins.  Wikipedia accessed 2018 Oct 18  Narrower terms: protein crystallography, X-ray crystallography, synchrotron- based x-ray crystallography  -- or are these equivalent?  Related term: Industrial Macromolecular Crystallography Association

Dalton: Unit of mass equal to the unified atomic mass (atomic mass  constant). [IUPAC Compendium] After John Dalton (1766-1844) British chemist and physicist. more Chemistry

deuterium- decoupled triple- resonance NMR: Gives an improvement in sensitivity.  If you randomly change some of the hydrogens in the sample to deuterium, then all of the other peaks in the spectrum can be made sharper, and the pulse sequence can be designed to erase, or decouple, the resonance- splitting effects of deuterium. 

FT-NMR: Fourier Transform NMR: Fourier-transform NMR spectrometers use a pulse of radiofrequency (RF) radiation to cause nuclei in a magnetic field to flip into the higher-energy alignment. Due to the Heisenberg uncertainty principle, the frequency width of the RF pulse (typically 1-10 µs) is wide enough to simultaneously excite nuclei in all local environments. All of the nuclei will re-emit RF radiation at their respective resonance frequencies, creating an interference pattern in the resulting RF emission versus time, known as a free-induction decay (FID). The frequencies are extracted from the FID by a Fourier transform of the time-based data. Technische Universität Braunschweig

flexible linkages: In proteins.

free induction decay FID: See spin, FT-NMR 

Hydrogen isotope used in NMR labeling.

hr-MAS High Resolution Magic Angle Spinning: The sample is spun at a high speed at a well-defined angle to the main magnetic field. Orienting the sample in this manner is a technique that was developed originally for solid state NMR to minimize the spectral line broadening introduced by intermolecular dipolar coupling or sample inhomogeneity. The appeal of hr-MAS is that it allows the study of systems that were previously not accessible with NMR. Some particularly interesting recent applications of this technology include the study of biological tissues and combinatorial chemistry samples that have been isolated on polymer beads.  Aileen Constans "Taking It Higher: State- of- the- Art NMR technology offers answers for the solution and solid states" Scientist 14 (21): 26, Oct. 30, 2000    Broader term: MAS Magic Angle Spinning 

high-field NMR: A type of spectroscopy where the energy states of spin-active nuclei placed in a static (>300 MHz) magnetic field are interrogated by inducing transitions between the states via radio frequency irradiation. Each experiment consists of a sequence of radio frequency pulses with delay periods in between them. Royal Society of Chemistry

The spectra of complex biomolecules contain a large number of peaks, many of which are close together or overlap. Higher field magnets, or higher frequency instruments, offer better peak resolution, enabling analysis of larger and larger molecules. Also, in NMR, sensitivity increases almost with the square of the magnetic field, so when magnetic field strength is doubled, sensitivity increases about fourfold. Data can thus be acquired faster, or alternatively, samples can be run at lower concentrations in the same experimental time. The latter advantage is particularly important to the study of large biomolecules, which are often difficult to express and purify in large quantities and can aggregate and precipitate out of solution at high concentrations. Finally, high- field NMR can lead to the development of new NMR experiments that exploit properties exhibited by molecules at high magnetic fields.  [Aileen Constans "Taking It Higher: State- of- the- Art NMR technology offers answers for the solution and solid states" Scientist 14 (21): 26, Oct. 30, 2000

high pressure NMR: Advanced high-resolution NMR spectroscopy, including two-dimensional NMR techniques, combined with high pressure capability, represents a powerful new tool in the study of proteins. High-Resolution, High-Pressure NMR Studies of Proteins J. Jonas,* L. Ballard,# and D. Nash# Biophysical Journal Volume 75 July 1998 445–452 

high-resolution diffusion-ordered spectroscopy HR-DOSY: Philip Hodge and Gareth Morris and their colleagues at the University of Manchester [are] using NMR to help them pick out the best host molecules from an array of hopefuls for use in analytical sensor applications. ... A multi- dimensional version of NMR, which disperses signals for the members of the library according to an additional criterion: their diffusion coefficients. Normally all the members will diffuse relatively rapidly. However, when a soluble polymer, with an added side-group of interest, is added to the combinatorial array, each member of the array that binds to the functionality on the polymer diffuses more slowly than before. The magnitude of the shift indicates the strength of the interaction. The spectrum of the most tightly bound molecule can then be plotted.  [Elemental Discoveries Mar. 2001, Issue 39]

hyphenated techniques: NMR together with chromatography and/ or mass spectrometry. Includes LC- NMR

Industrial Macromolecular Crystallography Association IMCA:  IMCA-CAT is a synchrotron-based structural biology research facility for industrial macromolecular crystallography aimed at accelerating pharmaceutical drug discovery programs.   IMCA-CAT is dedicated to high-throughput macromolecular crystallography for the pharmaceutical industry. The beamlines are equipped with robotics and automated for sample screening, ranking, data acquisition, and data processing.   Related terms: beamline, synchrotrons infrared spectromicroscopy: Microscopy

isotope: A form of a chemical element that contains the same number of protons but a different number of neutrons than other forms of the element. Isotopes are often used to trace atoms or molecules  in a metabolic pathway. In NMR, only one isotope of each element contains the correct magnetic properties to be useful.  NIGMS, US Structures of Life glossary

J coupling: See spin-spin coupling.

kD: kilo Dalton. Also abbreviated kDa.

macromolecular crystallography: a technique used to study biological molecules such as proteins, viruses and nucleic acids (RNA and DNA) to a resolution higher than ~5Å. This high resolution helps elucidate the detailed mechanism by which these macromolecules carry out their functions in living cells and organisms. Protein molecules can crystallize under regulated conditions; the crystals are made up of multiple copies of the molecule arranged in a regular 3-dimensional lattice. The x-rays deflected ("scattered") by the atoms in equivalent positions in the crystal lattice concentrate into sharp intense spots (crystal diffraction pattern). The macromolecular structure can be determined by analysis of the intensities and positions of the diffraction spots. Stanford Synchrotron Radiaiton Lightsource SLAC National Accelerator Laboratory

MAD Multiwavelength Anomalous Diffraction :
An approach to solving the phase problem in protein structure determination by comparing structure factors collected at different wavelengths, including the absorption edge of a heavy-atom scatterer. Also known as multiple-wavelength anomalous diffraction or multiwavelength anomalous dispersion.

A technique used in X-ray crystallography that accelerates the determination of protein structures. It uses X-rays of different wavelengths, relieving crystallographers from having to make several different metal- containing crystals.  NIGMS, US Structures of Life glossary

MAS Magic Angle Spinning: NMR strategy in which the tube is rotated at very high speed and at a  specific angle which cancels out the line broadening effects of inhomogeneities in the sample. This yields high resolution and high sensitivity which are very useful in trace analysis or in looking at solid phase synthesis resins. IUPAC Combinatorial Chemistry   Narrower term: hrMAS

mmCIF dictionary Macromolecular Crystallographic Information File glossary, Protein Data Bank MMCIF 

multidimensional (three- and four-dimensional) NMR:  This technology has the advantage of resolving the severe overlap in 2D spectra and represents a very important breakthrough. Related terms:  3D NMR, 4D NMR

15N: Nitrogen isotope label for NMR.

neutron crystallography: Neutron crystallography has had an important, but relatively small role in structural biology over the years. In this review of recently determined neutron structures, a theme emerges of a field currently expanding beyond its traditional boundaries, to address larger and more complex problems, with smaller samples and shorter data collection times, and employing more sophisticated structure determination and refinement methods. The origin of this transformation can be found in a number of advances including first, the development of neutron image-plates and quasi-Laue methods at nuclear reactor neutron sources and the development of time-of-flight Laue methods and electronic detectors at spallation neutron sources; second, new facilities and methods for sample perdeuteration and crystallization; third, new approaches and computational tools for structure determination. Neutron crystallography: opportunities, challenges, and limitations. Matthew P Blakeley,1 Paul Langan,2,3 Nobuo Niimura,4 and Alberto Podjarny5 Curr Opin Struct Biol. 2008 Oct;18(5):593-600. Epub 2008 Aug 7.

neutron scattering: Because of the neutron's particular properties, it is possible to obtain information on biomolecular structures, dynamics and interactions that is not accessible to other methodologies and neutron-scattering experiments should play an essential role if we hope to achieve a reasonable understanding of biology at the molecular level. The special advantages of neutrons combined with the progress in biochemistry and molecular biology are powerful reasons to stimulate a rebirth of neutron-scattering experiments in biology in the post genome sequencing era. Neutrons in biology in the post genome sequencing era G. Zaccai Applied Physics A: Materials Science & Processing Volume 74, Supplement 1, s6-s10, DOI: 10.1007/s003390101253        

NMR Nuclear Magnetic Resonance:  NMR spectroscopy makes it possible to discriminate nuclei, typically protons, in different chemical environments. The electron distribution gives rise to a chemical shift of the resonance frequency. The chemical shift, , of a nucleus is expressed in parts per million (ppm) by its frequency, n, relative to a standard, ref, and defined as = 106 (n - ref)/o, where o is the operating frequency of the spectrometer. It is an indication of the chemical state of the group containing the nucleus. More information is derived from the spin- spin couplings between nuclei, which give rise to multiplet patterns. Greater detail may be derived from two- or three- dimensional techniques. These use pulses of radiation at different nuclear frequencies, after which the response of the spin system is recorded as a free- induction decay (FID). Multi- dimensional techniques, such as COSY and NOESY, make it possible to deduce the structure of a relatively complex molecule such as a small protein (molecular weight up to 25 000). In proteins containing paramagnetic centres, nuclear hyperfine interactions can give rise to relatively large shifts of resonant frequencies known as contact and pseudo- contact (dipolar) shifts, and considerable increases in the nuclear spin relaxation rates. From this type of measurement, structural information can be obtained about the paramagnetic site. IUPAC Bioinorganic

A technology for protein structure determination. NMR generally gives a lower- resolution structure than X-ray crystallography does, but it does not require crystallization. NMR is currently applicable only to smaller proteins. Narrower terms:  2D NMR, 3D NMR, 4D NMR, COSY, deuterium decoupled triple resonance NMR, high field NMR, LC-NMR, multidimensional NMR, NMR - biomolecular, NOESY, ROESY, reduced dimensionality triple resonance NMR, SAR by NMR, STD NMR, solid state NMR, solution state NMR, TOCSY, TROSY, FT-NMR Fourier Transform NMR triple resonance NMR.  Related term: ESR Electron Spin Resonance

NMR active atom:
An atom that has the correct magnetic properties to be useful for NMR. For some atoms, the NMR-active form is a rare isotope, such as 13C or 15N. NIGMS, US Structures of Life glossary,

NMR Nuclear Magnetic Resonance - biomolecular: NMR spectroscopy on small- to medium- size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope. MeSH, 1998

NMR spin relaxation spectroscopy: A powerful approach for characterizing intramolecular and overall rotational motions in proteins. This review describes experimental methods for measuring laboratory frame spin relaxation rate constants by high- resolution solution- state NMR spectroscopy, together with theoretical approaches for interpreting spin relaxation data in order to quantify protein conformational dynamics on picosecond- nanosecond time scales. AG Palmer 3rd NMR probes of molecular dynamics: overview and comparison with other techniques. Annual Rev Biophys Biomol Struct.30:129- 155, 2001

NOE Nuclear Overhauser Effect: The interaction between the dipole moments of two nuclei in spatial proximity, provides information about the distance between nuclei and is one of the parameters studied in multidimensional  NMR.  Aileen Constans "Taking It Higher: State- of- the- Art NMR technology offers answers for the solution and solid states" Scientist 14 (21): 26, Oct. 30, 2000]     
Wikipedia  Related term: NOESY

NOESY  Nuclear Overhauser Effect (NOE)  SpectroscopY: An NMR technique used to help determine protein structures. It reveals how close different protons (hydrogen nuclei) are to each other in space.  NIGMS, US Structures of Life glossary
NOESY, ROESY and TROESY: what is the difference?
 FAQ 98-08.1 NMR FAQ, Chemistry Dept. Univ. of Alberta, Canada 

NOESY spectra: Allow the space interactions between atoms to be measured and generate a 3D structure of the protein. 

phasing techniques: Include Multiple Anonymous Dispersion MAD phasing, Multiple Isomorphous Replacement MIR Bernhard Rupp, Protein Crystallography Tutorial Site, 2005 

protein crystallography: Crystallography is a widely recognized tool that supports protein science. For Membrane Proteins, this tool is elevated into an important science that aids in the efforts to reveal structures and functions. This course describes how crystallography works, including highlights of Membrane Proteins and automation. For stable protein-protein and protein–nucleic acid complexes, mechanistic understanding comes most readily with the highest levels of structural detail (general shape). Thus, atomic resolution generally is the ultimate goal in analysis of any biological structure. Crystallography and some imaging techniques offer this potential but have very specialized sample requirements and limitations, are not high throughput, and provide only a static picture of the complex. DOE, Genomics GTL Roadmap: Molecular Machines 2005

Is there any kind of protein crystallography that isn't x-ray crystallography?  

pulse sequence: The application of a set of radio frequencies to a sample to produce a specific form of an NMR signal.  Many different types of pulse sequences have been designed for modulating the NMR signal; pulse sequences allow the optimization of the NMR signal for the study of different types of samples. The result is a sharpening of all the peaks and a significant improvement their signal- to- noise ratios and their value for structural analysis.  

pulsed field gradients PFG: Indicating that a probe is capable of doing gradient -enhanced spectroscopy. Glossary, AO-VNMR, Univ. of Alberta, Canada 

ROESY: Rotating frame Overhauser Enhancement SpectroscopY

reduced dimensionality triple resonance NMR: Being pioneered by people like Professor Thomas Szyperski at the State University of New York in Buffalo to exploit the higher sensitivity of cryogenic probesRelated term: triple resonance NMR

relaxation: Passage of an excited or otherwise perturbed system towards or into thermal equilibrium with its environment.  [IUPAC Photochemistry] Narrower term: chemical relaxation 

residual dipolar coupling: A relatively new way to measure relative orientations of bonds with respect to one another.  In NMR structure determination, distances are measured between atoms and interatomic distances are converted into 3D structures.  Now relative orientations of bonds can also be measured to give many more constraints, allowing structures to be determined more precisely, or being able to deal with larger proteins. 

resonance assignments: An early step in the process of NMR- based structure determination can be done rapidly for proteins up to approximately 30 kDa.  Although resonance assignments do not provide the complete structure of a protein, they often provide important structural information about a protein’s binding site, which can then be used to determine function. 

SAR by NMR Structure Activity Relationship by Nuclear Magnetic Resonance: Developed by Stephen Fesik of Abbott Laboratories. Allows the rapid screening and evaluation of thousands of compounds against a target protein. This screening technology detects whether a compound interacts by binding to the target protein, and it may also identify the binding epitope on the target. Different compounds may bind to adjacent, but different, sites. The next step in the SAR by NMR approach is to create structure- based- designed chemical libraries that link fragments of the original hits to yield high-potency leads. This method, however, requires a complete sequence- specific resonance assignment of the NMR- spectrum, which is still a time- consuming effort. 

site-directed NMR analysis: Understanding how ligands bind to a protein target is an essential part of drug development. Binding characteristics help determine how well the drug works - how effective and selective it is, and whether it can be administered in reasonable quantities. Traditionally, protein- ligand binding has been studied using X-ray crystallography (co- crystallography). But this approach can be  time- consuming and does not allow researchers to see how the drug works in solution.  Now it is becoming more common to use NMR for studies of ligand- binding conformations (i.e., a small molecule bound to a protein target). Related term site-specific screening.

site-specific screening: Researchers at the new Pharmacia spin- off, Biovitrum, also use NMR for structure- based, site- specific screening.  Conceived of by Mats Wikstrom, head of macromolecular structures at Biovitrum, this method uses site- specific isotopic labeling of two amino acid residues, a technique described by Masatune  Kainosho (Tokyo Metropolitan University) ...  In this approach, two amino acid types are labeled with 13C and 15N.  If this pair of amino acids occurs only once in the sequence, there will be only one peak in a one- dimensional/ two- dimensional HNCO- type NMR spectrum. This technique allows researchers to screen for only those binders that interact with a specific site of the receptor.  Also referred to as site- directed NMR.

solid state NMR: Requires wider- bore (63 or even 89 mm diameter) magnets [than solution state NMR]. The higher stored energy of  these wide bore magnets means that they are significantly more difficult to build, and as a result high- field solid state NMR lags behind liquid state in terms of available field strength. The highest field currently available for a wide bore magnet is 800 MHz .  [Aileen Constans "Taking It Higher: State- of- the- Art NMR technology offers answers for the solution and solid states" Scientist 14 (21): 26, Oct. 30, 2000]  

Can be used to study proteins that cannot be crystallized or are too large for  solution state NMR methods.

solution-based techniques: such as cryoEM, NMR, and X-ray and neutron diffraction offer information that is lower resolution but can be related more directly to the molecule’s structure in a more natural environment. Multiple tools obviously will be needed to obtain a more complete view of the structure of protein complexes, including shape, relationship of interaction faces, and stoichiometry. DOE, Genomics GTL Roadmap: Molecular Machines 2005 

solution state NMR: NMR in liquids

spin: The nuclei of certain atoms, for example, 1H, 13C, and 15N, exhibit a physical property known as spin. These nuclei can be viewed as tiny magnets that, when placed in an external magnetic field, can orient themselves in two possible ways, with spin vectors aligned in the direction of, or directly against, the field. For nuclei with a nuclear quantum spin number of 1/2, such as those listed above, these two orientations correspond, respectively, to a low energy state and a high- energy state. Transitions between the two states occur spontaneously, but infrequently. However, if the sample is irradiated with energy equivalent to the energy difference between the two states - in the radio frequency, or RF, range - transitions will occur more frequently. These induced transitions form the basis of NMR spectroscopy. When the magnetization vectors associated with the transitions are rotated perpendicular to the applied field, they precess about the direction of the field and induce a current in the receiver coil, which is recorded and plotted as a function of time. The resulting sine wave decays with time due to spin dephasing, and the signal is recorded as a free induction decay (FID), which is then converted into a frequency domain spectrum.  [Aileen Constans "Taking It Higher: State- of- the- Art NMR technology offers answers for the solution and solid states" Scientist 14 (21): 26, Oct. 30, 2000 Related terms spin labels, spin probes, spin properties, spin- spin coupling, spin- spin relaxation.

spin labels: A stable paramagnetic group that is attached to a part of another molecular entity whose microscopic environment is of interest and may be revealed by the electron paramagnetic resonance spectrum of the spin label. When a simple paramagnetic molecular entity is used in this way without covalent attachment to the molecular entity of interest it is frequently referred to as a "spin probe". IUPAC Bioinorganic Narrower terms:  1H,  13C, 15N.

spin properties: IUPAC Provisional Recommendations: NMR Nomenclature: Nuclear Spin Properties and Conventions for Chemical Shifts, Physical and Biophysical Chemistry Division, Commission Molecular Structure and Spectroscopy

spin-spin coupling: The interaction between the spin magnetic moments of different electrons and/or nuclei. In NMR spectroscopy it gives rise to multiplet patterns, and cross- peaks in two- dimensional NMR spectra. Between electron and nuclear spins this is termed the nuclear hyperfine interaction. Between electron spins it gives rise to relaxation effects and splitting of the EPR spectrum. IUPAC Bioinorganic     Is this the same as J coupling ?

spin-spin relaxation: A solid- state physics process involving raising temperatures using weak magnetic fields.

Superconducting QUantum Interference Devices SQUIDs: The most sensitive magnetic field detector ever devised ... SQUIDs have been used in NMR measurements since the 1980s, but mostly for solid samples at extremely low temperatures... SQUIDs can detect magnetic flux directly, sensing the magnetic field generated by even a slowly precessing nucleus. The resulting signal is weak but extremely sharp: the lower the magnetic field, the narrower the NMR line, yielding a signal- to- noise ratio far superior to that of high- field NMR.  Paul Preuss "Measuring molecules with minute magnetic fields" Lawrence Berkeley Lab, US, 2002

synchrotrons: Devices for accelerating protons or electrons in closed orbits where the accelerating voltage and magnetic field strength varies (the accelerating voltage is held constant for electrons) in order to keep the orbit radius constant. MeSH, 1993

A large machine that accelerates electrically charged particles to nearly the speed of light and maintains them in circular orbits. Originally designed for use by high- energy physicists, synchrotrons are now heavily used by structural biologists as a source of very intense X- rays.  NIGMS, US Structures of Life glossary,

A key development in the high throughput crystallographic solving of protein structures, shortening X-ray diffraction data collection time from days to hours and reducing the size of crystals needed to produce useful data. Terry Gaasterland “Structural genomics: Bioinformatics in the driver’s seat” Nature Biotechnology 16:625- 627 July 1998   Related terms: beamline, Industrial Macromolecular Crystallography Association IMCA; 
Synchrotron X-ray sources in the world
, ESRF European Synchrotron Radiation Facility 

TOCSY: TOtal Correlation SpectroscopY

TROESY: Transverse Rotating Frame Overhauser Effect Spectroscopy. 

TROSY Transverse Relaxation Optimized Spectroscopy: Invented about 1997. First described by Professor Kurt Wuthrich. Useful for analyzing larger protein systems. TROSY is a method for getting sharper peaks on large proteins.

TROSY is best at higher fields. If the aim is to study a large complex or a chemical shift perturbation when a protein binds to a receptor using NMR, it’s better to use a 900 MHz machine than a more standard lower- field machine.

triple-resonance NMR: Introduced in 1989, involves isotope labeling with 15N and 13C. (N = nitrogen; C = carbon.). Methods and software for automated analysis of now becoming available.

X-ray crystallography: The most widely used (and most accurate) method of obtaining structures, X-ray crystallography involves expressing highly purified protein samples, crystallizing these, and then performing X-ray diffraction of the protein to elucidate crystal structure.  Computational software is then used (combined with extensive - but increasingly less - human judgment) to convert X-ray diffraction data into high- resolution structures. Note that many proteins cannot be crystallized at present.

X-ray crystallography is an experimental technique that exploits the fact that X-rays are diffracted by crystals. It is not an imaging technique.  Bernard Rupp, Crystallography 101  
Related terms: beamlines, protein crystallography, synchrotrons

X-ray diffraction: <investigation> Basis of powerful technique for determining the three dimensional structure of molecules, including complex biological macromolecules such as proteins and nucleic acids, that form crystals or regular fibres. Low angle X-ray diffraction is also used to investigate higher levels of ordered structure, as found in muscle fibres.  OMD 18 Nov 1997

NMR & Crystallography resources
Clark, Jim, Understanding Chemistry, Nuclear Magnetic Resonance menu
Hornak, JP, Basics of NMR: Glossary,  Rochester Institute of Technology, US 1997-1999
IUCR International Union of Crystallography, Statistical descriptors in Crystallography, Glossary of statistical terms, 1996
IUPAC Recommendations: NMR Nomenclature: Nuclear Spin Properties and Conventions for Chemical Shifts, Robin K. Harris et. al, Physical and Biophysical Chemistry Division, Commission Molecular Structure and Spectroscopy, 2001
IUPAC Recommendations for the Presentation of NMR Structures of Proteins and Nucleic Acids, John L Markley et. al. July 28, 1998 
Joint Center for Structural Genomics, Important Definitions, 40+ terms 
Otter, Albin, AO-VNMR Glossary, Chemistry Dept. Univ. of Alberta, Canada, 2001.  About 50 terms. Click on Glossary
Rupp, Bernhard, Crystallography 101, 
SLAC Glossary, Stanford Linear Accelerator Center, Stanford Univ. US, 2002, 300 definitions. http://www.slac. slacspeak/

How to look for other unfamiliar  terms

IUPAC definitions are reprinted with the permission of the International Union of Pure and Applied Chemistry.

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