Eu3+ binding to europium-regenerated bacteriorhodopsin upon delipidation and monomerization

TitleEu3+ binding to europium-regenerated bacteriorhodopsin upon delipidation and monomerization
Publication TypeJournal Article
Year of Publication2004
AuthorsHeyes, CD, Reynolds, KB, EL-Sayed, MA
JournalFebs Letters
Volume562
Pagination207-210
Date PublishedMar
ISBN Number0014-5793
Accession NumberWOS:000220553000036
Abstract

We have studied the effect of monomerization of the purple membrane lattice, as well as removal of 75% of the lipids, on the binding properties of Eu3+ ions. We found that delipidation and monomerization do not cause the cations to lose their binding ability to the protein. This suggests that the three most strongly bound Eu3+ cations do not bind to the lipids, but directly bind to the protein. Furthermore, we found that delipidation actually causes a slight increase in the binding affinity. This is likely a result of reduced aggregation of europium-regenerated bacteriorhodopsin (bR) upon lipid removal causing more exposure of the binding sites to the Eu3+ cations. These results, taken with those from our previous publication [Heyes and El-Sayed, Biophys. J. 85 (2003) 426-434], might suggest that the cations remain bound upon delipidation of bR, but have no effect on the function. This is discussed with respect to the role of cations in the function of native bR. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.

DOI10.1016/s0014-5793(04)00182-6