A New Gd3+ Spin Label for Gd3+鈥揋d3+ Distance Measurements in Proteins Produces Narrow Distance Distributions

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• 作者：Elwy H. Abdelkader ; Michael D. Lee ; Akiva Feintuch ; Marie Ramirez Cohen ; James D. Swarbrick ; Gottfried Otting ; Bim Graham ; Daniella Goldfarb
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：December 17, 2015
• 年：2015
• 卷：6
• 期：24
• 页码：5016-5021
• 全文大小：408K
• ISSN：1948-7185

文摘

Gd³⁺ tags have been shown to be useful for performing distance measurements in biomolecules via the double electron鈥揺lectron 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⁺鈥揋d³⁺ 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⁺鈥揋d³⁺ 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.