Showing papers by "Christian Griesinger published in 2001"
TL;DR: Application of the self-consistent procedure presented here to dipolar coupling measurements of biomolecules aligned in different liquid-crystalline media should allow one to extract in a "model-free" way average orientations of dipolar vectors and specific aspects of their motions.
Abstract: The effects of internal motions on residual dipolar NMR couplings of proteins partially aligned in a liquid-crystalline environment are analyzed using a 10 ns molecular dynamics (MD) computer simulation of ubiquitin. For a set of alignment tensors with different orientations and rhombicities, MD-averaged dipolar couplings are determined and subsequently interpreted for different scenarios in terms of effective alignment tensors, average orientations of dipolar vectors, and intramolecular reorientational vector distributions. Analytical relationships are derived that reflect similarities and differences between motional scaling of dipolar couplings and scaling of dipolar relaxation data (NMR order parameters). Application of the self-consistent procedure presented here to dipolar coupling measurements of biomolecules aligned in different liquid-crystalline media should allow one to extract in a "model-free" way average orientations of dipolar vectors and specific aspects of their motions.
269 citations
TL;DR: High resolution magic-angle-spinning nuclear magnetic resonance experiments are used to show that two out of threen-decyl-ubiquinones bind at the ubiquinol oxidation center of the complex, substantiates a proposed mechanism in which a charge transfer between a Ubiquinol/ubiqu inone pair explains the bifurcation of electron flow.
63 citations
TL;DR: It is shown that ambiguities due to the 3 cosu-1 dependence of one cross-Correlated relaxation rate can be overcome by measuring additional cross-correlated relaxation rates.
Abstract: c Theory, experimental aspects, and use in structure calculation of cross-correlated relaxation rates measured on zeroand doublequantum coherences in liquid state NMR are presented The relative size of the interaction depends on the projection angle between the two tensorial interactions The tensorial interaction can be either a dipolar interaction or a chemical shift anisotropy relaxation mechanism (CSA) Effects of additional sources of relaxation on the cross-correlated relaxation rates are analyzed Also, an easy-to-use formalism is given to manipulate different cross-correlated relaxation interactions The application addresses measurement of the backbone angle c in a protein by measuring dipole(N–H)–dipole(C–H) and CSA(N)–dipole(C– H) cross-correlated relaxation rates It is shown that ambiguities due to the 3 cosu-1 dependence of one cross-correlated relaxation rate can be overcome by measuring additional cross-correlated relaxation rates The use of cross-correlated relaxation rates is demonstrated in structure calculations © 2000 Academic Press
58 citations
TL;DR: In this article, the relative orientation and dynamics of the monosaccharide moieties with respect to each other can be determined with the help of 13C, 1H and 1H,1H dipolar couplings, which can easily be measured.
Abstract: Residual dipolar couplings have dramatically improved the accuracy and precision of high-resolution NMR structures during the last years. This was first demonstrated for proteins. In this article, we describe, with raffinose and saccharose as examples, that dipolar couplings improve the precision of structures of carbohydrates for which usually very few structural parameters are available. The relative orientation as well as the dynamics of the monosaccharide moieties with respect to each other can be determined with the help of 13C,1H and 1H,1H dipolar couplings, which can easily be measured. Significant differences between the solution and the X-ray crystal structure exist. These results indicate that residual dipolar-coupling data may provide a more complete and dynamic model of carbohydrates in particular, and small molecules in general.
50 citations
TL;DR: In this article, modified phase-cycled Carr-Purcell-type multiple-pulse sequences are optimized for coherence and polarization transfer in homonuclear Hartmann-Hahn experiments applied to partially oriented samples.
35 citations
TL;DR: The conformations of methylene‐H4MPT in solution and when enzyme‐bound by using NMR spectroscopy and semiempirical quantum mechanical calculations are determined and it is shown that changing this conformation into an activated one in which the pro‐R hydrogen atom is antiperiplanar to the lone electron pair of N10 probably predetermines the Re‐face stereospecificity of the four dehydrogenases.
Abstract: Four different dehydrogenases are known that catalyse the reversible dehydrogenation of N5,N10-methylenetetrahydromethanopterin (methylene-H4MPT) or N5,N10-methylenetetrahydrofolate (methylene-H4F) to the respective N5,N10-methenyl compounds. Sequence comparison indicates that the four enzymes are phylogenetically unrelated. They all catalyse the Re-face-stereospecific removal of the pro-R hydrogen atom of the coenzyme's methylene group. The Re-face stereospecificity is in contrast to the finding that in solution the pro-S hydrogen atom of methylene-H4MPT and of methylene-H4F is more reactive to heterolytic cleavage. For a better understanding we determined the conformations of methylene-H4MPT in solution and when enzyme-bound by using NMR spectroscopy and semiempirical quantum mechanical calculations. For the conformation free in solution we find an envelope conformation for the imidazolidine ring, with the flap at N10. The methylene pro-S C-H bond is anticlinal and the methylene pro-R C-H bond is synclinal to the lone electron pair of N10. Semiempirical quantum mechanical calculations of heats of formation of methylene-H4MPT and methylene-H4F indicate that changing this conformation into an activated one in which the pro-S C-H bond is antiperiplanar, resulting in the preformation of the leaving hydride, would require a deltadeltaH(f) of +53 kJ mol-1 for methylene-H4MPT and of +51 kJ mol-1 for methylene-H4F. This is almost twice the energy required to force the imidazolidine ring in the enzyme-bound conformation of methylene-H4MPT (+29 kJ mol-1) or of methylene-H4F (+35 kJ mol-1) into an activated conformation in which the pro-R hydrogen atom is antiperiplanar to the lone electron pair of N10. The much lower energy for pro-R hydrogen activation thus probably predetermines the Re-face stereospecificity of the four dehydrogenases. Results are also presented explaining why the chemical reduction of methenyl-H4MPT+ and methenyl-H4F+ with NaBD4 proceeds Si-face-specific, in contrast to the enzyme-catalysed reaction.
21 citations
TL;DR: The structural basis for the extraordinary stability of a triple-stranded oligonucleotide in which the third strand contains 2'-aminoethoxy-substituted riboses is investigated by NMR spectroscopy and a new NMR method relies on CH-CH dipolar-dipolar cross-correlated relaxation rates to investigate the conformational preference of the aminoethoxy side chain.
Abstract: The structural basis for the extraordinary stability of a triple-stranded oligonucleotide in which the third strand contains 2‘-aminoethoxy-substituted riboses is investigated by NMR spectroscopy. The enhanced stability of the modified triplex in comparison to the unmodified DNA triplex of the same sequence can be attributed to strong interactions of the aminoethoxy groups of the third strand with the phosphate groups of the purine strand. In molecular dynamics calculations the aminoethoxy side chain was found to be rather flexible, allowing for the presence of hydrogen bonds between the aminoethoxy group of the third strand and two different phosphates of the backbone of the second strand. To investigate the conformational preference of the aminoethoxy side chain a new NMR method has been developed which relies on CH−CH dipolar−dipolar cross-correlated relaxation rates. The results indicate that the aminoethoxy side chains adopt mainly a gauche+ conformation, for which only one of the two hydrogen bonds ...
20 citations
TL;DR: It was found that the pro-R hydrogen of methylene‐H4MPT is transferred by MtdA into the pro‐R position of NADPH.
8 citations
TL;DR: In this paper, a new heteronuclear NMR pulse sequence for the measurement of nJ(C,H) coupling constants, α/βselective HC(C)H-TOCSY, is described.
Abstract: A new heteronuclear NMR pulse sequence for the measurement of nJ(C,H) coupling constants, the α/βselective HC(C)H-TOCSY, is described It is shown that the S3E element (Meissner et al, 1997a,b) can be used to obtain spin state selective coherence transfer in molecules, in which adjacent CH moieties are labeled with 13C Application of the α/β selective HC(C)H-TOCSY to a 10nt RNA tetraloop 5′-CGCUUUUGCG-3′, in which the four uridine residues are 13C labeled in the sugar moiety, allowed measurement of two bond and three bond J(C,H) coupling constants, which provide additional restraints to characterize the sugar ring conformation of RNA in cases of conformational averaging
8 citations
TL;DR: Aizawa et al. as discussed by the authors proposed a two-component regulatory system for transmembrane signalling in bacteria, which consists of a membraneous sensory histidine protein kinase and a cytoplasmic response regulator.
Abstract: In bacteria various types of signal transduction proteins are used for the perception of environmental signals (Aizawa et al., 2000). Most of the sensors receive the signal at the periplasmic side of the membrane. By transferring the signal across the membrane, it is converted into a cellular signal, which is used for regulation of transcription, enzyme activity, or flagellar rotation. Two-component regulatory systems represent the most frequent systems of this type for transmembrane signalling in bacteria. They consist of a membraneous sensory histidine protein kinase and a cytoplasmic response regulator. Signal transfer between the sensor and the response regulator is effected by protein phosphorylation. In the facultative anaerobic bacterium Escherichia coli the switch from aerobic to anaerobic metabolism is regulated at the transcriptional level in response to the electron acceptors O2, nitrate, and fumarate. The expression of the genes of anaerobic fumarate respiration, including fumarate reductase, an anaerobic C4-dicarboxylate (fumarate) carrier, and of fumarase B, is regulated by C4-dicarboxylates and the twocomponent regulatory system DcuSR (dicarboxylate uptake) (Zientz et al., 1998; Golby et al., 1999). The DcuSR system consists of the sensor DcuS located in the cytoplasmic membrane, and of the cytoplasmic response regulator DcuR. DcuS contains two transmembrane helices, one periplasmic domain, and the
6 citations
TL;DR: Paraca et al. as discussed by the authors presented the Paraca-Vogtherrc-Fiebigc-Vergnaud-Maurerd (Pahle) method for the detection of carcinogenic compounds in Organische Chemie.
Abstract: Tatjana N. Paraca,b, Martin Vogtherrc, Marcus Maurerd, Andreas Pahle, Heinz Ruterjansf, Christian Griesingera,g & Klaus Fiebigc,∗ aInstitut fur Organische Chemie der Universitat Frankfurt, Marie-Curie-Str. 11, 60439 Frankfurt, Germany; bK.U. Leuven, Department of Chemistry, Celestijnenlaan 200F, B-3001 Heverlee, Belgium; cMRPharm, MarieCurie-Str. 11, D-60439 Frankfurt, Germany; dAstaMedica, Weismullerstr. 45, D-60314 Frankfurt, Germany; eInstitut fur Pharmakologie und Toxikologie, Universitat Erlangen, Germany; fInstitut fur Biophysikalische Chemie der Universitat Frankfurt, Marie-Curie-Str. 11, D-60439 Frankfurt, Germany; gMax-Planck-Institut fur Biophysikalische Chemie, Am Fasberg 11, D-37077 Gottingen, Germany
TL;DR: The title compound, C5H6N+·CH3SO3−, shows pseudosymmetry as discussed by the authors, where more than 80% of the structure is centrosymmetric, whereas the remaining atoms do not fulfil this symmetry.
Abstract: The title compound, C5H6N+·CH3SO3−, shows pseudosymmetry. More than 80% of the structure is centrosymmetric, whereas the remaining atoms do not fulfil this symmetry, and the structure is actually non-centrosymmetric.
TL;DR: Employing combinatorial chemistry methods, small peptide ligands were found, which bind to a short RNA with important biological functions, which are an attractive therapeutic target.
Abstract: RNA, as one of the biomolecules with the most structural and functional diversity, is an attractive therapeutic target.(1) Employing combinatorial chemistry methods, small peptide ligands were found, which bind to a short RNA with important biological functions. A 23-nt RNA oligonucleotide from the cholesterol ester transfer protein mRNA was chosen as a molecular target.(2) A 27-nt RNA oligonucleotide from the human immunodeficiency virus type-1 (HIV-1) TAR RNA was used to control the binding specificity.(3) Tetrapeptide libraries, composed of the amino acids Lys, Tyr, Leu, Ile, and Arg, with and without C- and N-terminal lysines, were synthesized by a combination of combinatorial and divergent solid-phase synthesis. Gel-shift affinity screening was used to extract the peptides with the best RNA binding properties. The peptide Lys-Tyr-Lys-Leu-Tyr-Lys-Cys-NH(2) (1) showing micromolar affinity to its RNA target was characterized with circular dichroism (CD), ultra violet (UV) measurement, and (1)H NMR spectroscopy.
TL;DR: Paraca et al. as discussed by the authors presented the Paraca-Vogtherrc-Fiebigc-Vergnaud-Maurerd (Pahle) method for the detection of carcinogenic compounds in Organische Chemie.
Abstract: Tatjana N. Paraca,b, Martin Vogtherrc, Marcus Maurerd, Andreas Pahle, Heinz Ruterjansf, Christian Griesingera,g & Klaus Fiebigc,∗ aInstitut fur Organische Chemie der Universitat Frankfurt, Marie-Curie-Str. 11, 60439 Frankfurt, Germany; bK.U. Leuven, Department of Chemistry, Celestijnenlaan 200F, B-3001 Heverlee, Belgium; cMRPharm, MarieCurie-Str. 11, D-60439 Frankfurt, Germany; dAstaMedica, Weismullerstr. 45, D-60314 Frankfurt, Germany; eInstitut fur Pharmakologie und Toxikologie, Universitat Erlangen, Germany; fInstitut fur Biophysikalische Chemie der Universitat Frankfurt, Marie-Curie-Str. 11, D-60439 Frankfurt, Germany; gMax-Planck-Institut fur Biophysikalische Chemie, Am Fasberg 11, D-37077 Gottingen, Germany
TL;DR: Human oncoproteinMDM2 reveals a MHC class I binding motif HMDM441 characterizing MDM2 as a potential tumor antigen which is present in lysate and supernatant of a human hepatoma cell line overexpressing normal 90-kDa MDM 2.
01 Jan 2001
TL;DR: This work evaluated the immunological reactivity of polyclonal human anti-HIV antibodies from patient sera against a solid phase decapeptide library derived from HIV-1 V3 sequence data in order to achieve a minimal set of peptides with orthogonal seroreactivites against different subtypes.
Abstract: The V3-loop is an immunodominant region within the envelope protein of HIV-1. Peptides of this region are used to classify HIV-1 into subtypes based on the seroreactivity of patients’ sera. However, correlation between genetically determined subtypes and their seroreactivity is not yet fully established. Therefore, new approaches have been pursued [1]. We evaluated the immunological reactivity of polyclonal human anti-HIV antibodies from patient sera against a solid phase decapeptide library derived from HIV-1 V3 sequence data in order to achieve a minimal set of peptides with orthogonal seroreactivites against different subtypes. This approach serves as a basis to establish an immunofluorescence based assay for subtyping HIV-1.