Volume 60, Issue 28 pp. 15445-15451
Research Article

The Role of Rotational Motion in Diffusion NMR Experiments on Supramolecular Assemblies: Application to Sup35NM Fibrils

Dr. Boris B. Kharkov

Dr. Boris B. Kharkov

Laboratory of Biomolecular NMR, St. Petersburg State University, 199034 St. Petersburg, Russia

These authors contributed equally to this work.

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Ivan S. Podkorytov

Ivan S. Podkorytov

Laboratory of Biomolecular NMR, St. Petersburg State University, 199034 St. Petersburg, Russia

These authors contributed equally to this work.

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Dr. Stanislav A. Bondarev

Dr. Stanislav A. Bondarev

Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia

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Dr. Mikhail V. Belousov

Dr. Mikhail V. Belousov

Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia

Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia

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Vladislav A. Salikov

Vladislav A. Salikov

Laboratory of Biomolecular NMR, St. Petersburg State University, 199034 St. Petersburg, Russia

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Prof. Dr. Galina A. Zhouravleva

Prof. Dr. Galina A. Zhouravleva

Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia

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Prof. Dr. Nikolai R. Skrynnikov

Corresponding Author

Prof. Dr. Nikolai R. Skrynnikov

Laboratory of Biomolecular NMR, St. Petersburg State University, 199034 St. Petersburg, Russia

Department of Chemistry, Purdue University, West Lafayette, IN, 47907 USA

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First published: 23 April 2021
Citations: 2

Graphical Abstract

Diffusion of amyloid fibrils that contain disordered domains can be captured by pulsed-field-gradient NMR experiments. A new theory is presented that interprets the results of these measurements in terms of fibrils’ translational and rotational motion. Application to Sup35NM fibrils demonstrates the feasibility of diffusion-based sorting in complex amyloidogenic samples.

Abstract

Pulsed-field gradient (PFG) NMR is an important tool for characterization of biomolecules and supramolecular assemblies. However, for micrometer-sized objects, such as amyloid fibrils, these experiments become difficult to interpret because in addition to translational diffusion they are also sensitive to rotational diffusion. We have constructed a mathematical theory describing the outcome of PFG NMR experiments on rod-like fibrils. To test its validity, we have studied the fibrils formed by Sup35NM segment of the prion protein Sup35. The interpretation of the PFG NMR data in this system is fully consistent with the evidence from electron microscopy. Contrary to some previously expressed views, the signals originating from disordered regions in the fibrils can be readily differentiated from the similar signals representing small soluble species (e.g. proteolytic fragments). This paves the way for diffusion-sorted NMR experiments on complex amyloidogenic samples.

Conflict of interest

The authors declare no conflict of interest.

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