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

Junji Iwahara, Chun Tang, G. Marius Clore

Research output: Contribution to journalArticle

162 Citations (Scopus)

Abstract

The use of 1H 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 1H transverse relaxation rates (Γ2). We first show that accurate Γ2 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 Γ2, unless a relatively long repetition delay is employed. We then examine the field dependence of Γ2, and show that Γ2 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 Γ2 measurements. Errors in Γ2 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 Γ2 measurement.

Original languageEnglish (US)
Pages (from-to)185-195
Number of pages11
JournalJournal of Magnetic Resonance
Volume184
Issue number2
DOIs
StatePublished - Feb 2007
Externally publishedYes

Fingerprint

Macromolecules
macromolecules
augmentation
Contamination
contamination
Error analysis
Magnetic Fields
repetition
Magnetic fields
intervals
probes
magnetic fields
Experiments

Keywords

  • H-T
  • EDTA-Mn
  • Paramagnetic relaxation enhancement
  • Spin-label

ASJC Scopus subject areas

  • Molecular Biology
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Radiology Nuclear Medicine and imaging
  • Condensed Matter Physics

Cite this

Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules. / Iwahara, Junji; Tang, Chun; Marius Clore, G.

In: Journal of Magnetic Resonance, Vol. 184, No. 2, 02.2007, p. 185-195.

Research output: Contribution to journalArticle

@article{9aaaaa12af1c4a77985435bed3e312bd,
title = "Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules",
abstract = "The use of 1H 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 1H transverse relaxation rates (Γ2). We first show that accurate Γ2 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 Γ2, unless a relatively long repetition delay is employed. We then examine the field dependence of Γ2, and show that Γ2 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 Γ2 measurements. Errors in Γ2 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 Γ2 measurement.",
keywords = "H-T, EDTA-Mn, Paramagnetic relaxation enhancement, Spin-label",
author = "Junji Iwahara and Chun Tang and {Marius Clore}, G.",
year = "2007",
month = "2",
doi = "10.1016/j.jmr.2006.10.003",
language = "English (US)",
volume = "184",
pages = "185--195",
journal = "Journal of Magnetic Resonance",
issn = "1090-7807",
publisher = "Academic Press Inc.",
number = "2",

}

TY - JOUR

T1 - Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules

AU - Iwahara, Junji

AU - Tang, Chun

AU - Marius Clore, G.

PY - 2007/2

Y1 - 2007/2

N2 - The use of 1H 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 1H transverse relaxation rates (Γ2). We first show that accurate Γ2 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 Γ2, unless a relatively long repetition delay is employed. We then examine the field dependence of Γ2, and show that Γ2 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 Γ2 measurements. Errors in Γ2 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 Γ2 measurement.

AB - The use of 1H 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 1H transverse relaxation rates (Γ2). We first show that accurate Γ2 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 Γ2, unless a relatively long repetition delay is employed. We then examine the field dependence of Γ2, and show that Γ2 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 Γ2 measurements. Errors in Γ2 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 Γ2 measurement.

KW - H-T

KW - EDTA-Mn

KW - Paramagnetic relaxation enhancement

KW - Spin-label

UR - http://www.scopus.com/inward/record.url?scp=33846561471&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33846561471&partnerID=8YFLogxK

U2 - 10.1016/j.jmr.2006.10.003

DO - 10.1016/j.jmr.2006.10.003

M3 - Article

C2 - 17084097

AN - SCOPUS:33846561471

VL - 184

SP - 185

EP - 195

JO - Journal of Magnetic Resonance

JF - Journal of Magnetic Resonance

SN - 1090-7807

IS - 2

ER -