@article {Dell'Orco923_2016,
	year = {2016},
	author = {Dell'Orco, Daniele and Koch, Karl-Wilhelm},
	title = {Fingerprints of calcium-binding protein conformational dynamics monitored by surface plasmon resonance},
	journal = {ACS chemical biology},
	ISSN = {1},
	abstract = {Surface plasmon resonance (SPR) spectroscopy is widely used to probe interactions involving biological macromolecules by detecting changes in the refractive index in a metal/dielectric interface following the dynamic formation of a molecular complex. In the last years SPR-based experimental approaches were developed to monitor conformational changes induced by the binding of small analytes to proteins coupled to the surface of commercially available sensor chips. A significant contribution to our understanding of the phenomenon came from the study of several Ca2+-sensor proteins operating in diverse cellular scenarios, in which the conformational switch is triggered by specific Ca2+ signals. Structural and physicochemical analyses demonstrated that the SPR signal not only depends on the change in protein size upon Ca2+-binding but likely originates from variations in the hydration shell structure. The resulting changes in the dielectric properties of water or of the protein-water interface eventually reflect different crowding conditions on the SPR sensor chip, which mimic the cellular environment. SPR could hence be used to monitor conformational transitions in proteins, especially when a significant variation in the hydrophobicity of the solvent-exposed protein surface occurs, thus leading to changes in the dielectric milieu of the whole sensor chip surface. We review recent work in which SPR has been successfully employed to provide a fingerprint of the conformational change dynamics in proteins under native and altered conditions, which include posttranslational modifications, co-presence of competing analytes and point mutations of single amino acids associated to genetic diseases}
}