Do conformational changes contribute to the surface plasmon resonance signal?

0572387 - BFÚ 2024 RIV NL eng J - Journal Article
Dobrovodský, Daniel - Di Primo, C.
Do conformational changes contribute to the surface plasmon resonance signal?
Biosensors and Bioelectronics. Roč. 232, JUL 15 2023 (2023), č. článku 115296. ISSN 0956-5663. E-ISSN 1873-4235
R&D Projects: GA MŠMT EF15_003/0000477
Institutional support: RVO:68081707
Keywords : Surface plasmon resonance * Conformational change * G-quadruplex * Refractive index increment * Thrombin binding aptamer
OECD category: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)
Impact factor: 12.6, year: 2022
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S0956566323002385?via%3Dihub

Surface plasmon resonance (SPR)-based biosensors are widely used instruments for characterizing molecular interactions. In theory the SPR signal depends only on mass changes for interacting molecules of same chemical nature. Whether conformational changes of interacting molecules also contribute to the SPR signal is still a subject of lively debates. Works have been published claiming that conformational changes were detected but all factors contributing to the SPR signal were not carefully considered, in addition to often using no or improper controls. In the present work we used a very well-characterized oligonucleotide, the thrombin-binding DNA aptamer (TBA), which upon binding of potassium ions folds into a two G-tetrad antiparallel G-quadruplex structure. All terms contributing to the maximal expected SPR response, Rmax, in particular the refractive index increment, RII, of both partners and the fraction of immobilized TBA target available, ca, were experimentally assessed. The resulting Rmax was then compared to the maximal experimental SPR response for potassium ions binding to TBA using appropriate controls. Regardless how the RIIs were measured, by SPR or refractometry, and how much TBA available for interacting with potassium ions was considered, the theoretical and the experi-mental SPR responses never matched, the former being always lower than the latter. Using a straightforward experimental model system and by thoroughly taking into account all contributing factors we therefore conclude that conformational changes can indeed contribute to the measured SPR signal.
Permanent Link: https://hdl.handle.net/11104/0350035