What question did this study set out to answer?

To determine the structural basis of weakly ordered z-axis anisotropic motion observed for the nitroxide spin label R1 at diverse protein surface sites.

February 23, 2009Protein ScienceOpen Access

Structural origin of weakly ordered nitroxide motion in spin‐labeled proteins

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To determine the structural basis of weakly ordered z-axis anisotropic motion observed for the nitroxide spin label R1 at diverse protein surface sites.
Solved crystal structures of spin-labeled R1 at solvent-exposed helical sites (131 and 151) and a loop site (82) in T4 lysozyme under cryogenic and ambient temperatures.
Analyzed structural rotamers and noncovalent interactions alongside electron paramagnetic resonance (EPR) dynamic spectra.
Helical sites 131R1 and 151R1 revealed an intraresidue C(alpha)–H...S(delta) interaction that immobilizes the disulfide group, confirming that internal motion is governed by terminal bond rotations.
The 131R1 side chain populated two distinct rotamers equally despite displaying a single dominant EPR dynamic population, indicating both rotamers share internal motion dictated by the disulfide-backbone interaction.
Loop site 82R1 retained the identical disulfide-backbone interaction, proving that the interaction is independent of secondary structure and establishing that EPR spectral changes at surface sites reliably report backbone motion.

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Implication

Structural analysis reveals an immobilizing disulfide-backbone interaction in spin-labeled T4 lysozyme, indicating that label dynamics reflect underlying backbone motion.

Cite This Study

Fleissner et al. (2009) studied this question.

synapsesocial.com/papers/6a9027d4d27faa463b908fcc https://doi.org/10.1002/pro.96

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Implication

Structural analysis reveals an immobilizing disulfide-backbone interaction in spin-labeled T4 lysozyme, indicating that label dynamics reflect underlying backbone motion.

Structural origin of weakly ordered nitroxide motion in spin‐labeled proteins

Key Points

Discussion

Implication

Cite This Study

Structural origin of weakly ordered nitroxide motion in spin‐labeled proteins

Key Points

Discussion

Implication

Cite This Study

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