Biophysical Journal 69: 2056-2059 (1995)
© 1995 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yang, D Articles by el-Sayed, M A Search for Related Content PubMed PubMed Citation Articles by Yang, D Articles by el-Sayed, M A

The Ca2+ binding to deionized monomerized and to retinal removed bacteriorhodopsin.

School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332-0400, USA.

ABSTRACT

In our continuing effort to characterize the metal cation binding in bacteriorhodopsin (bR) using Ca(2+)-specific electrodes, potentiometric titration was carried out on deionized solubilized bR (containing monomeric units) and deionized bacterioopsin (bR with its retinal removed). Scatchard plots were analyzed. The monomer was found to have plots similar to those of the trimer, suggesting that the binding sites in bR are localized within the protein monomer unit and not between the molecules within the trimer structure. This also supports the previous assumption that the curvature in the Scatchard plot of regenerated bR is not due to cooperativity of metal cation within the trimer, but rather due to multiple sites. Recent studies further support the finding that the curved Scatchard plot is not due to the cooperativity between the metal ions in the two high affinity sites, wherever they are. The results of the analysis of the Scatchard plot for deionized bacterioopsin have shown a change in the binding characteristics of the high affinity but not the low affinity sites from that observed in bR. This result supports previous conclusions that metal cations in the high affinity sites are not far from the retinal cavity.

This article has been cited by other articles:

				F. Sepulcre, M. G. Proietti, M. Benfatto, S. Della Longa, J. Garcia, and E. Padros A Quantitative XANES Analysis of the Calcium High-Affinity Binding Site of the Purple Membrane Biophys. J., July 1, 2004; 87(1): 513 - 520. [Abstract] [Full Text] [PDF]

				C. Roselli, A. Boussac, T. A. Mattioli, J. A. Griffiths, and M. A. El-Sayed Detection of a Yb3+ binding site in regenerated bacteriorhodopsin that is coordinated with the protein and phospholipid head groups PNAS, December 10, 1996; 93(25): 14333 - 14337. [Abstract] [Full Text] [PDF]