DEER distance measurements on trityl/trityl and Gd(iii)/trityl labelled proteins.

A new interesting article has been published in Phys Chem Chem Phys. 2019 May 22;21(20):10217-10227. doi: 10.1039/c8cp07249c. and titled:

DEER distance measurements on trityl/trityl and Gd(iii)/trityl labelled proteins.

Authors of this article are:

Giannoulis A , Yang Y , Gong YJ , Tan X , Feintuch A , Carmieli R , Bahrenberg T , Liu Y , Su XC , Goldfarb D .

A summary of the article is shown below:

Triarylmethyl (TAM or trityl) radicals are becoming important for measuring distances in proteins and nucleic acids. Here, we report on a new trityl spin label CT02MA, which conjugates to a protein via a redox stable thioether bond. The performance of the new spin label was demonstrated in W-band double electron-electron resonance (DEER) distance measurements on doubly trityl-labelled mutants of immunoglobulin G-binding protein 1 (GB1) and ubiquitin. For both doubly CT02MA-labelled proteins we measured, by applying chirped pump pulse(s), relatively narrow distance distributions, comparable to those obtained with the same protein mutants doubly labelled with BrPy-DO3MA-Gd(iii). We noticed, however, that the sample contained some free CT02MA that was difficult to remove at the purification step. Dual labelling of ubiquitin with one CT02MA tag and one BrPy-DO3MA-Gd(iii) tag was achieved as well and the trityl-Gd(iii) distance distribution was measured, facilitated by the use of a dual mode cavity in combination with a chirped pump pulse. We also measured the Gd(iii)-Gd(iii) distance distribution in this sample, showing that the labelling procedure was not fully selective. Nevertheless, these measurements demonstrate the potential of the high sensitivity Gd(iii)-trityl W-band DEER distance measurements in proteins, which can be further exploited by designing orthogonal Gd(iii)/trityl labelling schemes.

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This article is a good source of information and a good way to become familiar with topics such as: Carrier Proteins; Chemistry Techniques, Analytical; Gadolinium; Mutation; Proteins; Ubiquitin.