Molecular motion of spin labeled side chains in α-helices: Analysis by variation of side chain structure

L. Columbus, T. Kálai, J. Jekö, K. Hideg, W. L. Hubbell

Research output: Contribution to journalArticle

220 Citations (Scopus)

Abstract

Two single cysteine substitution mutants at helix surface sites in T4 lysozyme (D72C and V131C) have been modified with a series of nitroxide methanethiosulfonate reagents to investigate the structural and dynamical origins of their electron paramagnetic resonance spectra. The novel reagents include 4-substituted derivatives of either the pyrroline or pyrrolidine series of nitroxides. The spectral line shapes were analyzed as a function of side chain structure and temperature using a simulation method with a single order parameter and diffusion rates about three orthogonal axes as parameters. Taken together, the results provide strong support for an anisotropic motional model of the side chain, which was previously proposed from qualitative features of the spectra and crystal structures of spin labeled T4 lysozyme. Site-specific differences in apparent order parameter are interpreted in terms of backbone dynamics modes with characteristic correlation times in the nanosecond or faster time scale. The saturated 4-substituted pyrrolidine nitroxides are shown to be a suitable template for novel "functionalized" side chains designed to mimic salient features of the native side chains they replace.

Original languageEnglish
Pages (from-to)3828-3846
Number of pages19
JournalBiochemistry
Volume40
Issue number13
DOIs
Publication statusPublished - Apr 3 2001

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Muramidase
Electron Spin Resonance Spectroscopy
Cysteine
Paramagnetic resonance
Substitution reactions
Crystal structure
Derivatives
Temperature
pyrrolidine
methanethiosulfonate
pyrroline

ASJC Scopus subject areas

  • Biochemistry

Cite this

Molecular motion of spin labeled side chains in α-helices : Analysis by variation of side chain structure. / Columbus, L.; Kálai, T.; Jekö, J.; Hideg, K.; Hubbell, W. L.

In: Biochemistry, Vol. 40, No. 13, 03.04.2001, p. 3828-3846.

Research output: Contribution to journalArticle

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