High-resolution NMR of encapsulated proteins dissolved in low-viscosity fluids

Wand, A. Joshua; Ehrhardt, Mark R.; Flynn, Peter F.

doi:10.1073/pnas.95.26.15299

Cited by 123 publications

(170 citation statements)

References 33 publications

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“…Furthermore, the Stokes-Einstein equation [Eq. (4)] demonstrates that the tumbling time of an isotropically reorientating (spherical) molecule is linearly related to the bulk solvent viscosity: [25] …”

Section: Discussionmentioning

confidence: 99%

Probing Platinum Azido Complexes by ¹⁴N and ¹⁵N NMR Spectroscopy

Farrer

Gierth

Sadler

2011

Chemistry A European J

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Metal azido complexes are of general interest due to their high energetic properties, and platinum azido complexes in particular because of their potential as photoactivatable anticancer prodrugs. However, azido ligands are difficult to probe by NMR spectroscopy due to the quadrupolar nature of (14)N and the lack of scalar (1)H coupling to enhance the sensitivity of the less abundant (15)N by using polarisation transfer. In this work, we report (14)N and (15)N NMR spectroscopic studies of cis,trans,cis-[Pt(N(3))(2)(OH)(2)(NH(3))] (1) and trans,trans,trans-[Pt(N(3))(2)(OH)(2)(X)(Y)], where X=Y=NH(3) (2); X=NH(3), Y=py (3) (py=pyridine); X=Y=py (4); and selected Pt(II) precursors. These studies provide the first (15)N NMR data for azido groups in coordination complexes. We discuss one- and three-bond J((15)N,(195)Pt) couplings for azido and am(m)ine ligands. The (14)N(α) (coordinated azido nitrogen) signal in the Pt(IV) azido complexes is extremely broad (W(1/2)≈2124 Hz for 4) in comparison to other metal azido complexes, attributable to a highly asymmetrical electric field gradient at the (14)N(α) atom. Through the use of anti-ringing pulse sequences, the (14)N NMR spectra, which show resolution of the broad (14)N(α) peak, were obtained rapidly (e.g., 1.5 h for 10 mM 4). The linewidths of the (14)N(α) signals correlate with the viscosity of the solvent. For (15) N-enriched samples, it is possible to detect azido (15)N resonances directly, which will allow photoreactions to be followed by 1D (15)N NMR spectroscopy. The T(1) relaxation times for 3 and 4 were in the range 5.7-120 s for (15)N, and 0.9-11.3 ms for (14)N. Analysis of the (1)J((15)N,(195)Pt) coupling constants suggests that an azido ligand has a moderately strong trans influence in octahedral Pt(IV) complexes, within the series 2-pic

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Section: Discussionmentioning

confidence: 99%

Probing Platinum Azido Complexes by ¹⁴N and ¹⁵N NMR Spectroscopy

Farrer

Gierth

Sadler

2011

Chemistry A European J

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“…The increases of effective molecular size and bulk solvent viscosity can both contribute to the global change in relaxation parameters (33). Therefore, PFG-NMR diffusion experiments were used to discriminate between those.…”

Section: Substantial Chemical Shift Changes Indicate a Strong Dependementioning

confidence: 99%

NMR Study of Mersacidin and Lipid II Interaction in Dodecylphosphocholine Micelles

Hsu

Breukink

Bierbaum

et al. 2003

Journal of Biological Chemistry

125

119

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“…In these experiments the AOT RMs are dissolved in low-viscosity solvent, in order to increase the tumbling speed of the confined protein. 24,25 Proof-of-principle studies have shown that the structure of ubiquitin does not change significantly upon encapsulation, although there are some changes in the dynamics.…”

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confidence: 99%

Simulations of the confinement of ubiquitin in self-assembled reverse micelles

Tian

Garcı́a

2011

The Journal of Chemical Physics

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We describe the effects of confinement on the structure, hydration, and the internal dynamics of ubiquitin encapsulated in reverse micelles (RM). We performed molecular dynamics simulations of the encapsulation of ubiquitin into self-assembled protein/surfactant reverse micelles to study the positioning and interactions of the protein with the RM and found that ubiquitin binds to the RM interface at low salt concentrations. The same hydrophobic patch that is recognized by ubiquitin binding domains in vivo is found to make direct contact with the surfactant head groups, hydrophobic tails, and the iso-octane solvent. The fast backbone N-H relaxation dynamics show that the fluctuations of the protein encapsulated in the RM are reduced when compared to the protein in bulk. This reduction in fluctuations can be explained by the direct interactions of ubiquitin with the surfactant and by the reduced hydration environment within the RM. At high concentrations of excess salt, the protein does not bind strongly to the RM interface and the fast backbone dynamics are similar to that of the protein in bulk. Our simulations demonstrate that the confinement of protein can result in altered protein dynamics due to the interactions between the protein and the surfactant.

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High-resolution NMR of encapsulated proteins dissolved in low-viscosity fluids

Cited by 123 publications

References 33 publications

Probing Platinum Azido Complexes by ¹⁴N and ¹⁵N NMR Spectroscopy

Probing Platinum Azido Complexes by ¹⁴N and ¹⁵N NMR Spectroscopy

NMR Study of Mersacidin and Lipid II Interaction in Dodecylphosphocholine Micelles

Simulations of the confinement of ubiquitin in self-assembled reverse micelles

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High-resolution NMR of encapsulated proteins dissolved in low-viscosity fluids

Cited by 123 publications

References 33 publications

Probing Platinum Azido Complexes by 14N and 15N NMR Spectroscopy

Probing Platinum Azido Complexes by 14N and 15N NMR Spectroscopy

NMR Study of Mersacidin and Lipid II Interaction in Dodecylphosphocholine Micelles

Simulations of the confinement of ubiquitin in self-assembled reverse micelles

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Probing Platinum Azido Complexes by ¹⁴N and ¹⁵N NMR Spectroscopy

Probing Platinum Azido Complexes by ¹⁴N and ¹⁵N NMR Spectroscopy