Spin-label-induced nuclear relaxation. Distances between bound saccharides, histidine-15, and tryptophan-123 on lysozyme in solution

Wien, R.; Morrisett, Joel D.; McConnell, Harden M.

doi:10.1021/bi00770a008

Cited by 107 publications

(40 citation statements)

References 27 publications

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“…For a very large system with τ r larger than 50 ns (corresponding to a molecular weight in excess of 100 kDa), the contribution could be larger than 20% at 800 MHz. In the case of a nitroxide spin label, the electron spin relaxation time τ s (>10 −7 s) is much longer than τ r (35,36) and, therefore, the PRE correlation time τ c , defined as (τ r −1 +τ s −1 ) −1 , is virtually identical to τ r , resulting in a field-independent 1 H-Γ 2 . For a macromolecular system with conjugated EDTA-Mn 2+ , on the other hand, τ s is comparable to τ r (10,19,20) and consequently 1 H-Γ 2 could be field-dependent because of the field-dependence of τ s .…”

Section: Field-dependence Of 1 H-γmentioning

confidence: 99%

Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules

Iwahara

Tang

Clore

2007

Journal of Magnetic Resonance

245

385

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The use of 1 H transverse paramagnetic relaxation enhancement (PRE) has seen a resurgence in recent years as method for providing long-range distance information for structural studies and as a probe of large amplitude motions and lowly populated transient intermediates in macromolecular association. In this paper we discuss various practical aspects pertaining to accurate measurement of PRE 1 H transverse relaxation rates (Γ 2 ). We first show that accurate Γ 2 rates can be obtained from a two time-point measurement without requiring any fitting procedures or complicated error estimations, and no additional accuracy is achieved from multiple time-point measurements recorded in the same experiment time. Optimal setting of the two time-points that minimize experimental errors is also discussed. Next we show that the simplistic single time-point measurement that has been commonly used in the literature, can substantially underestimate the true value of Γ 2 , unless a relatively long repetition delay is employed. We then examine the field dependence of Γ 2 , and show that Γ 2 exhibits only a very weak field dependence at high magnetic fields typically employed in macromolecular studies. The theoretical basis for this observation is discussed. Finally, we investigate the impact of contamination of the paramagnetic sample by trace amounts (≤5%) of the corresponding diamagnetic species on the accuracy of Γ 2 measurements. Errors in Γ 2 introduced by such diamagnetic contamination are potentially sizeable, but can be significantly reduced by using a relatively short time interval for the two time-point Γ 2 measurement.

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Section: Field-dependence Of 1 H-γmentioning

confidence: 99%

Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules

Iwahara

Tang

Clore

2007

Journal of Magnetic Resonance

245

385

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“…Correlation ti~ncs for rotational rcoricntation were dctcrmincd using the quadratic tcrm of the ratio-of-heights mcthod of McConncll and co-workers (20). assuming isotropic nitroxidc tumbling.…”

Section: Genercrl ~Nrrhocls Cr~rcl Trlcrtericrl\mentioning

confidence: 99%

Some chemical and analytical aspects of polysaccharide modifications. IV. Electron spin resonance studies of nitroxide-labelled chitin and chitosan derivatives

Yalpani¹,

Hall²

1984

Can. J. Chem.

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Nitroxide spin labels have been attached to chitin, chitosan, and their derivatives in order to investigate the solution and gel characteristics of these polymers. Thus, chitin was nonselectively acylated using the chloroacetamide label 3 to afford. the corresponding nitroxide derivative 4. Selective and nonselective labelling of chitosan was accomplished either via reductive alkylation using the keto label 5 and sodium cyanoborohydride or via a chitosan sulfate intermediate using labels 3 or 5. Two branched water soluble chitosan derivatives, carrying C-6 oxidized, terminal galactose side chains were selectively labelled by reductive animation using the amine label 13 to yield derivatives 14 and 15. Motional correlation values of the covalently-linked nitroxide moieties were shown to reflect the nature of the linkage between spin label and polymer, as well as structural differences between the branch residues of derivatives 14 and 15. The spin-probe – spin-label method was employed to demonstrate structural heterogeneities for the chitosan derivatives 7 and 15.

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“…The stoichiometry of labelling was determined by hydrolyzing the labelled enzyme with I M NaOH for 24 hr at 60°C. 6 ) The spectral amplitude of the hydrolysate was then compared to a standard curve of similarly prepared spin label. EPR spectra were measured in 25111 capillary tubes with a Varian E-109 century series spectrometer (Varian Associates, Palo Alto, CA.)…”

mentioning

confidence: 99%

Spin-labelling and Differential Scanning Calorimetry Study of the Denaturation of Aspartic Proteinases from the Fungi Endothia parasitica and Mucor miehei

Brown

Yada

1991

Agricultural and Biological Chemistry

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Spin-label-induced nuclear relaxation. Distances between bound saccharides, histidine-15, and tryptophan-123 on lysozyme in solution

Cited by 107 publications

References 27 publications

Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules

Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules

Some chemical and analytical aspects of polysaccharide modifications. IV. Electron spin resonance studies of nitroxide-labelled chitin and chitosan derivatives

Spin-labelling and Differential Scanning Calorimetry Study of the Denaturation of Aspartic Proteinases from the Fungi Endothia parasitica and Mucor miehei

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