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Yalloway, Gary N.; Löhr, Frank; Wienk, Hans; Mayhew, Stephen G.; Hrovat, Andrea; Knauf, Martin; Rüterjans, Heinz

doi:10.1023/a:1022814324367

Cited by 7 publications

(3 citation statements)

References 6 publications

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“…Resonance assignments were previously reported (BioMagRes database [48,49] accession codes given in parentheses) for oxidised Desulfovibrio vulgaris flavodoxin (BMRB-5571), [50,51] Aspergillus oryzae ribonuclease T1 (BMRB-133 and BMRB-1658), [52 -54] human frataxin (BMRB-4342), [55] human ubiquitin (BMRB-6466), [56] Bacillus agaradhaerens xylanase (BMRB-5352), [57] and Loligo vulgaris DFPase (BMRB-5618). [58] Flavodoxin Recombinant D. vulgaris flavodoxin was prepared as described previously.…”

Section: Experimental Protein Samples and Reference Structuresmentioning

confidence: 99%

Variation in protein C^α‐related one‐bond J couplings

Schmidt¹,

Howard²,

Maestre-Martínez³

et al. 2008

Magnetic Reson in Chemistry

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Four types of polypeptide (1)J(C alpha X) couplings are examined, involving the main-chain carbon C(alpha) and either of four possible substituents. A total 3105 values of (1)J(C alpha H alpha), (1)J(C alpha C beta), (1)J(C alpha C'), and (1)J(C alpha N') were collected from six proteins, averaging 143.4 +/- 3.3, 34.9 +/- 2.5, 52.6 +/- 0.9, and 10.7 +/- 1.2 Hz, respectively. Analysis of variances (ANOVA) reveals a variety of factors impacting on (1)J and ranks their relative statistical significance and importance to biomolecular NMR structure refinement. Accordingly, the spread in the (1)J values is attributed, in equal proportions, to amino-acid specific substituent patterns and to polypeptide-chain geometry, specifically torsions phi, psi, and chi(1) circumjacent to C(alpha). The (1)J coupling constants correlate with protein secondary structure. For alpha-helical phi, psi combinations, (1)J(C alpha H alpha) is elevated by more than one standard deviation (147.8 Hz), while both (1)J(C alpha N') and (1)J(C alpha C beta) fall short of their grand means (9.5 and 33.7 Hz). Rare positive phi torsion angles in proteins exhibit concomitant small (1)J(C alpha H alpha) and (1)J(C alpha N') (138.4 and 9.6 Hz) and large (1)J(C alpha C beta) (39.9 Hz) values. The (1)J(C alpha N') coupling varies monotonously over the phi torsion range typical of beta-sheet secondary structure and is largest (13.3 Hz) for phi around -160 degrees. All four coupling types depend on psi and thus help determine a torsion that is notoriously difficult to assess by traditional approaches using (3)J. Influences on (1)J stemming from protein secondary structure and other factors, such as amino-acid composition, are largely independent.

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Section: Experimental Protein Samples and Reference Structuresmentioning

confidence: 99%

Variation in protein C^α‐related one‐bond J couplings

Schmidt¹,

Howard²,

Maestre-Martínez³

et al. 2008

Magnetic Reson in Chemistry

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“…The reasons for the reduced overall intensity in the Cys102 strip are the faster transverse relaxation of its amide nuclei and the longer Δ period used. Of the two cross‐peaks in the low‐field half of the Asp95 strip, the one at 176.3 ppm is due to the intraresidual two‐bond coupling ( 2 J C′,N =0.35 Hz) while the second exactly matches the Cys93 13 C′ chemical shift55 such that it is tentatively assigned to a four‐bond interaction ( 4 J Cys93 C′,Asp95 N′ =0.23 Hz) along the protein main chain. In contrast, the large sequential and intraresidual correlations with Gly94 C′ ( δ =173.7 ppm) and Asp95 C γ ( δ =179.9 ppm), respectively, have been effectively suppressed.…”

Section: Resultsmentioning

confidence: 99%

Gaining Selectivity by Combining Catalysts: Sequential versus Recycling Processes

Fransson

Moberg

2010

ChemCatChem

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Highly enantioenriched chiral products may be obtained by using a combination of two moderately selective catalysts. Sequential enantioselective transformations comprising an asymmetric reaction followed by a kinetic resolution of the scalemic product mixture obtained in the first step are well known. In such processes, the minor, undesired enantiomer is transformed to a compound that can be more easily separated from the major enantiomer. Although chiral compounds may be obtained with high enantiopurity by such coupled processes, the yield of the desired product necessarily suffers. Recycling processes, whereby the minor enantiomer is transformed to prochiral starting material, avoid this limitation. In this Minireview, different types of sequential catalytic processes using two reinforcing catalysts are surveyed and their advantages and limitations discussed in relation to recycling processes.

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“…The FD from Desulfovibrio vulgaris has been extensively characterized electrochemically and by various forms of optical spectroscopy . Many mutants have been characterized, − the crystal structures of all three oxidation states have been solved , and NMR resonance assignments have been published for both the diamagnetic states. − The structure of flavodoxin is depicted in Figure and is unaffected by the flavin oxidation state, with the exception of residues 59–62 and 95–102 immediately adjacent to the flavin. ,− Thus, FD provides a robust and familiar system in which to explore the practicality of using a stable endogenous radical that participates in biological function, as a source of DNP.…”

Section: Introductionmentioning

confidence: 99%

¹H Dynamic Nuclear Polarization Based on an Endogenous Radical

et al. 2012

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We demonstrate a 15-fold enhancement of solid-state NMR signals via dynamic nuclear polarization (DNP) based on a stable, naturally occurring radical in a protein: the flavin mononucleotide (FMN) semiquinone of flavodoxin. The linewidth of flavodoxin’s EPR signal suggests that the dominant DNP mechanism is the solid effect, consistent with the field-dependent DNP enhancement profile. The magnitude of the enhancement as well as the bulk-polarization build-up time constant (τB) with which it develops are dependent on the isotopic composition of the protein. Deuteration of the protein to 85 % increased the nuclear longitudinal relaxation time T1n and τB by factors of five and seven, respectively. Slowed dissipation of polarization can explain the two-fold higher maximal enhancement than that obtained in proteated protein, based on the endogenous semiquinone. In contrast, the long τB of TOTAPOL-based DNP in non-glassy samples was not accompanied by a similarly important long T1n, and in this case the enhancement was greatly reduced. The low concentrations of radicals occurring naturally in biological systems limit the magnitude of DNP enhancement that is attainable by this means. However, our enhancement factors of up to 15 can nonetheless make an important difference to the feasibility of applying solid-state NMR to biochemical systems. We speculate that DNP based on endogenous radicals may facilitate MAS NMR characterization of biochemical complexes and even organelles, and could also serve as a source of additional structural and physiological information.

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Untitled

Cited by 7 publications

References 6 publications

Variation in protein C^α‐related one‐bond J couplings

Variation in protein C^α‐related one‐bond J couplings

Gaining Selectivity by Combining Catalysts: Sequential versus Recycling Processes

¹H Dynamic Nuclear Polarization Based on an Endogenous Radical

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Untitled

Cited by 7 publications

References 6 publications

Variation in protein Cα‐related one‐bond J couplings

Variation in protein Cα‐related one‐bond J couplings

Gaining Selectivity by Combining Catalysts: Sequential versus Recycling Processes

1H Dynamic Nuclear Polarization Based on an Endogenous Radical

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Product

Resources

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Variation in protein C^α‐related one‐bond J couplings

Variation in protein C^α‐related one‐bond J couplings

¹H Dynamic Nuclear Polarization Based on an Endogenous Radical