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The role of electrostatic interactions in calmodulin-peptide complex formation

André, Ingemar LU ; Kesvatera, Tönu LU ; Jönsson, Bo LU ; Akerfeldt, KS and Linse, Sara LU (2004) In Biophysical Journal 87(3). p.1929-1938
Abstract
The complex between calmodulin and the calmodulin-binding portion of smMLCKp has been studied. Electrostatic interactions have been anticipated to be important in this system where a strongly negative protein binds a peptide with high positive charge. Electrostatic interactions were probed by varying the pH in the range from 4 to 11 and by charge deletions in CaM and smMLCKp. The change in net charge of CaM from similar to-5 at pH 4.5 to -15 at pH 7.5 leaves the binding constant virtually unchanged. The affinity was also unaffected by mutations in CaM and charge substitutions in the peptide. The insensitivity of the binding constant to pH may seem surprising, but it is a consequence of the high charge on both protein and peptide. At low pH... (More)
The complex between calmodulin and the calmodulin-binding portion of smMLCKp has been studied. Electrostatic interactions have been anticipated to be important in this system where a strongly negative protein binds a peptide with high positive charge. Electrostatic interactions were probed by varying the pH in the range from 4 to 11 and by charge deletions in CaM and smMLCKp. The change in net charge of CaM from similar to-5 at pH 4.5 to -15 at pH 7.5 leaves the binding constant virtually unchanged. The affinity was also unaffected by mutations in CaM and charge substitutions in the peptide. The insensitivity of the binding constant to pH may seem surprising, but it is a consequence of the high charge on both protein and peptide. At low pH it is further attenuated by a charge regulation mechanism. That is, the protein releases a number of protons when binding the positively charged peptide. We speculate that the role of electrostatic interactions is to discriminate against unbound proteins rather than to increase the affinity for any particular target protein. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
87
issue
3
pages
1929 - 1938
publisher
Cell Press
external identifiers
  • wos:000223668500048
  • pmid:15345569
  • scopus:4444270810
ISSN
1542-0086
DOI
10.1529/biophysj.104.040998
language
English
LU publication?
yes
id
2ff9cf3a-b2ab-4bcd-b8dd-b051037d1fc5 (old id 139609)
date added to LUP
2007-06-29 08:29:14
date last changed
2017-11-05 03:38:55
@article{2ff9cf3a-b2ab-4bcd-b8dd-b051037d1fc5,
  abstract     = {The complex between calmodulin and the calmodulin-binding portion of smMLCKp has been studied. Electrostatic interactions have been anticipated to be important in this system where a strongly negative protein binds a peptide with high positive charge. Electrostatic interactions were probed by varying the pH in the range from 4 to 11 and by charge deletions in CaM and smMLCKp. The change in net charge of CaM from similar to-5 at pH 4.5 to -15 at pH 7.5 leaves the binding constant virtually unchanged. The affinity was also unaffected by mutations in CaM and charge substitutions in the peptide. The insensitivity of the binding constant to pH may seem surprising, but it is a consequence of the high charge on both protein and peptide. At low pH it is further attenuated by a charge regulation mechanism. That is, the protein releases a number of protons when binding the positively charged peptide. We speculate that the role of electrostatic interactions is to discriminate against unbound proteins rather than to increase the affinity for any particular target protein.},
  author       = {André, Ingemar and Kesvatera, Tönu and Jönsson, Bo and Akerfeldt, KS and Linse, Sara},
  issn         = {1542-0086},
  language     = {eng},
  number       = {3},
  pages        = {1929--1938},
  publisher    = {Cell Press},
  series       = {Biophysical Journal},
  title        = {The role of electrostatic interactions in calmodulin-peptide complex formation},
  url          = {http://dx.doi.org/10.1529/biophysj.104.040998},
  volume       = {87},
  year         = {2004},
}