A New Gd3+ Spin Label for Gd3+-Gd3+ Distance Measurements in Proteins Produces Narrow Distance Distributions

Elwy H. Abdelkader, Michael D. Lee, Akiva Feintuch, Marie Ramirez Cohen, James D. Swarbrick, Gottfried Otting*, Bim Graham, Daniella Goldfarb

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    41 Citations (Scopus)

    Abstract

    Gd3+ tags have been shown to be useful for performing distance measurements in biomolecules via the double electron-electron resonance (DEER) technique at Q- and W-band frequencies. We introduce a new cyclen-based Gd3+ tag that exhibits a relatively narrow electron paramagnetic resonance (EPR) spectrum, affording high sensitivity, and which yields exceptionally narrow Gd3+-Gd3+ distance distributions in doubly tagged proteins owing to a very short tether. Both the maxima and widths of distance distributions measured for tagged mutants of the proteins ERp29 and T4 lysozyme, featuring Gd3+-Gd3+ distances of ca. 6 and 4 nm, respectively, were well reproduced by simulated distance distributions based on available crystal structures and sterically allowed rotamers of the tag. The precision of the position of the Gd3+ ion is comparable to that of the nitroxide radical in an MTSL-tagged protein and thus the new tag represents an attractive tool for performing accurate distance measurements and potentially probing protein conformational equilibria.

    Original languageEnglish
    Pages (from-to)5016-5021
    Number of pages6
    JournalJournal of Physical Chemistry Letters
    Volume6
    Issue number24
    DOIs
    Publication statusPublished - 1 Dec 2015

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