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Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research
Open AccessArticle

XANES Measurements for Studies of Adsorbed Protein Layers at Liquid Interfaces

1
European Synchrotron Radiation Facility, 38043 Grenoble, France
2
National Research Center “Kurchatov Institute”, 123182 Moscow, Russia
3
Faculty of Physics, Southern Federal University, 344006 Rostov-on-Don, Russia
4
Bach Institute of Biochemistry, Federal Research Center of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia
5
Veltischev Research and Clinical Institute for Paediatrics, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
6
Moscow Institute of Physics and Technology, Dolgoprudny, 141701 Moscow Region, Russia
*
Author to whom correspondence should be addressed.
Materials 2020, 13(20), 4635; https://doi.org/10.3390/ma13204635
Received: 31 August 2020 / Revised: 8 October 2020 / Accepted: 12 October 2020 / Published: 17 October 2020
(This article belongs to the Special Issue Advanced Synchrotron Techniques for Soft and Nanomaterials)
X-ray absorption near edge structure (XANES) spectra for protein layers adsorbed at liquid interfaces in a Langmuir trough have been recorded for the first time. We studied the parkin protein (so-called E3 ubiquitin ligase), which plays an important role in pathogenesis of Parkinson disease. Parkin contains eight Zn binding sites, consisting of cysteine and histidine residues in a tetracoordinated geometry. Zn K-edge XANES spectra were collected in the following two series: under mild radiation condition of measurements (short exposition time) and with high X-ray radiation load. XANES fingerprint analysis was applied to obtain information on ligand environments around zinc ions. Two types of zinc coordination geometry were identified depending on X-ray radiation load. We found that, under mild conditions, local zinc environment in our parkin preparations was very similar to that identified in hemoglobin, treated with a solution of ZnCl2 salt. Under high X-ray radiation load, considerable changes in the zinc site structure were observed; local zinc environment appeared to be almost identical to that defined in Zn-containing enzyme alkaline phosphatase. The formation of a similar metal site in unrelated protein molecules, observed in our experiments, highlights the significance of metal binding templates as essential structural modules in protein macromolecules. View Full-Text
Keywords: metalloproteins; XANES; zinc binding sites; protein layers at liquid interface; Langmuir trough metalloproteins; XANES; zinc binding sites; protein layers at liquid interface; Langmuir trough
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Konovalov, O.V.; Novikova, N.N.; Kovalchuk, M.V.; Yalovega, G.E.; Topunov, A.F.; Kosmachevskaya, O.V.; Yurieva, E.A.; Rogachev, A.V.; Trigub, A.L.; Kremennaya, M.A.; Borshchevskiy, V.I.; Vakhrameev, D.D.; Yakunin, S.N. XANES Measurements for Studies of Adsorbed Protein Layers at Liquid Interfaces. Materials 2020, 13, 4635.

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