Structural and dynamic characterization of the urea denatured state of the immunoglobulin binding domain of streptococcal protein G by multidimensional heteronuclear NMR spectroscopy. 1995

M K Frank, and G M Clore, and A M Gronenborn
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA.

The structure and dynamics of the urea-denatured B1 immunoglobulin binding domain of streptococcal protein G (GB1) has been investigated by multidimensional heteronuclear NMR spectroscopy. Complete 1H, 15N, and 13C assignments are obtained by means of sequential through-bond correlations. The nuclear Overhauser enhancement, chemical shift, and 3JHN alpha coupling constant data provide no evidence for the existence of any significant population of residual native or nonnative ordered structure. 15N relaxation measurements at 500 and 600 MHz, however, provide evidence for conformationally restricted motions in three regions of the polypeptide that correspond to the second beta-hairpin, the N-terminus of the alpha-helix, and the middle of the alpha-helix in the native protein. The time scale of these motions is longer than the apparent overall correlation time (approximately 3 ns) and could range from about 6 ns in the case of one model to between 4 microseconds and 2 ms in another; it is not possible to distinguish between these two cases with certainty because the dynamics are highly complex and hence the analysis of the time scale of this slower motion is highly model dependent. It is suggested that these three regions may correspond to nucleation sites for the folding of the GB1 domain. With the exception of the N- and C-termini, where end effects predominate, the amplitude of the subnanosecond motions, on the other hand, are fairly uniform and model independent, with an overall order parameter S2 ranging from 0.4 to 0.5.

UI MeSH Term Description Entries
D007136 Immunoglobulins Multi-subunit proteins which function in IMMUNITY. They are produced by B LYMPHOCYTES from the IMMUNOGLOBULIN GENES. They are comprised of two heavy (IMMUNOGLOBULIN HEAVY CHAINS) and two light chains (IMMUNOGLOBULIN LIGHT CHAINS) with additional ancillary polypeptide chains depending on their isoforms. The variety of isoforms include monomeric or polymeric forms, and transmembrane forms (B-CELL ANTIGEN RECEPTORS) or secreted forms (ANTIBODIES). They are divided by the amino acid sequence of their heavy chains into five classes (IMMUNOGLOBULIN A; IMMUNOGLOBULIN D; IMMUNOGLOBULIN E; IMMUNOGLOBULIN G; IMMUNOGLOBULIN M) and various subclasses. Globulins, Immune,Immune Globulin,Immune Globulins,Immunoglobulin,Globulin, Immune
D008958 Models, Molecular Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures. Molecular Models,Model, Molecular,Molecular Model
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D011489 Protein Denaturation Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein. Denaturation, Protein,Denaturations, Protein,Protein Denaturations
D001426 Bacterial Proteins Proteins found in any species of bacterium. Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D001665 Binding Sites The parts of a macromolecule that directly participate in its specific combination with another molecule. Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013291 Streptococcus A genus of gram-positive, coccoid bacteria whose organisms occur in pairs or chains. No endospores are produced. Many species exist as commensals or parasites on man or animals with some being highly pathogenic. A few species are saprophytes and occur in the natural environment.
D014508 Urea A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids. Basodexan,Carbamide,Carmol
D017433 Protein Structure, Secondary The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to ALPHA-HELICES; BETA-STRANDS (which align to form BETA-SHEETS), or other types of coils. This is the first folding level of protein conformation. Secondary Protein Structure,Protein Structures, Secondary,Secondary Protein Structures,Structure, Secondary Protein,Structures, Secondary Protein
D017510 Protein Folding Processes involved in the formation of TERTIARY PROTEIN STRUCTURE. Protein Folding, Globular,Folding, Globular Protein,Folding, Protein,Foldings, Globular Protein,Foldings, Protein,Globular Protein Folding,Globular Protein Foldings,Protein Foldings,Protein Foldings, Globular

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