scholarly journals Simulating electron spin resonance spectra of nitroxide spin labels from molecular dynamics and stochastic trajectories

2008 ◽  
Vol 128 (16) ◽  
pp. 165106 ◽  
Author(s):  
Deniz Sezer ◽  
Jack H. Freed ◽  
Benoît Roux
Keyword(s):  
Molecular Dynamics ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Labels ◽  
Spin Resonance ◽  
Nitroxide Spin Labels

scholarly journals High-field electron spin resonance of spin labels in membranes

2002 ◽  
Vol 116 (1-2) ◽  
pp. 93-114 ◽  
Author(s):  
Derek Marsh ◽  
Dieter Kurad ◽  
Vsevolod A. Livshits
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
High Field ◽  
Spin Labels ◽  
Field Electron ◽  
Spin Resonance

Electron Spin Resonance Studies on Conformational Changes of the Sarcoplasmic Reticulum Ca2+ – ATPase Induced by Synergistic Action of Calcium and ATP

1981 ◽  
Vol 36 (9) ◽  
pp. 1136-1143 ◽  
Author(s):  
Peter Laggner ◽  
Josef Suko ◽  
Christian Punzengruber ◽  
Rudolf Prager
Keyword(s):  
Electron Spin Resonance ◽  
Sarcoplasmic Reticulum ◽  
Electron Spin ◽  
Conformational Changes ◽  
Environmental Changes ◽  
Adenine Nucleotides ◽  
Membrane Vesicles ◽  
Heterocyclic Ring ◽  
Spin Labels ◽  
Spin Resonance

Abstract Changes in motional properties of the -SH group environment in sarcoplasmic reticulum ATPase [1] induced by addition of specific ligands to sarcoplasmic reticulum membrane vesicles were investigated systematically by electron spin resonance (e.p.r.) spectroscopy. Alternatively, two kinds of iodoacetamide analog spin labels, 4-(2-iodoacetamido)- 2,2,5,5-tetramethyl-1-pyrrolidinyl-N-oxyl (label I) and 4-(2-iodoacetamido)-2,2,6,6-tetramethyl- 1-piperidinyl-N-oxyl (label II) were used. The labeling conditions were chosen such that less than three moles of -SH groups per mole of ATPase reacted with the spin labels. A marked increase in isotropic motion of either spin label was observed on addition of calcium in millimolar concentrations plus ATP or β-γ-methylene ATP. Qualitatively similar but smaller changes were also observed with inosine 5'-triphosphate (ITP), acetylphosphate, or ADP in the presence of calcium. These effects were independent of added magnesium. The spectral changes induced by β-γ-methylene ATP, which binds to the ATPase but is not hydrolyzed, and those of calcium plus ADP suggest a conformational change due to simultaneous binding of these ligands in the absence of enzyme phosphorylation. These changes in e.p.r. spectra were different in quality and magnitude from those observed upon separate binding of calcium or adenine nucleotides. The two spin labels, differing only in their numbers of heterocyclic ring atoms, were found to reflect environmental changes in different ways. This demonstrates the usefulness of employing different spin labels to detect and interpret structural transitions in macromolecular assemblies.

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