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pK(a) values for side-chain carboxyl groups of a PGB1 variant explain salt and pH-dependent stability

Lindman, Stina LU ; Linse, Sara LU ; Mulder, Frans LU and André, Ingemar LU (2007) In Biophysical Journal 92(1). p.257-266
Abstract
Determination of pK(a) values of titrating residues in proteins provides a direct means of studying electrostatic coupling as well as pH-dependent stability. The B1 domain of protein G provides an excellent model system for such investigations. In this work, we analyze the observed pK(a) values of all carboxyl groups in a variant of PGB1 (T2Q, N8D, N37D) at low and high ionic strength as determined using H-1-C-13 heteronuclear NMR in a structural context. The pK(a) values are used to calculate the pH-dependent stability in low and high salt and to investigate electrostatic coupling in the system. The observed pK(a) values can explain the pH dependence of protein stability but require pKa shifts relative to model values in the unfolded... (More)
Determination of pK(a) values of titrating residues in proteins provides a direct means of studying electrostatic coupling as well as pH-dependent stability. The B1 domain of protein G provides an excellent model system for such investigations. In this work, we analyze the observed pK(a) values of all carboxyl groups in a variant of PGB1 (T2Q, N8D, N37D) at low and high ionic strength as determined using H-1-C-13 heteronuclear NMR in a structural context. The pK(a) values are used to calculate the pH-dependent stability in low and high salt and to investigate electrostatic coupling in the system. The observed pK(a) values can explain the pH dependence of protein stability but require pKa shifts relative to model values in the unfolded state, consistent with persistent residual structure in the denatured state. In particular, we find that most of the deviations from the expected random coil values can be explained by a significantly upshifted pK(a) value. We show also that C-13 backbone carbonyl data can be used to study electrostatic coupling in proteins and provide specific information on hydrogen bonding and electrostatic potential at nontitrating sites. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
92
issue
1
pages
257 - 266
publisher
Cell Press
external identifiers
  • wos:000242754300031
  • scopus:33846011386
ISSN
1542-0086
DOI
10.1529/biophysj.106.088682
language
English
LU publication?
yes
id
1e40a881-87f4-4f8d-8798-758861b02ca0 (old id 682367)
date added to LUP
2007-12-17 08:42:16
date last changed
2017-06-11 03:45:58
@article{1e40a881-87f4-4f8d-8798-758861b02ca0,
  abstract     = {Determination of pK(a) values of titrating residues in proteins provides a direct means of studying electrostatic coupling as well as pH-dependent stability. The B1 domain of protein G provides an excellent model system for such investigations. In this work, we analyze the observed pK(a) values of all carboxyl groups in a variant of PGB1 (T2Q, N8D, N37D) at low and high ionic strength as determined using H-1-C-13 heteronuclear NMR in a structural context. The pK(a) values are used to calculate the pH-dependent stability in low and high salt and to investigate electrostatic coupling in the system. The observed pK(a) values can explain the pH dependence of protein stability but require pKa shifts relative to model values in the unfolded state, consistent with persistent residual structure in the denatured state. In particular, we find that most of the deviations from the expected random coil values can be explained by a significantly upshifted pK(a) value. We show also that C-13 backbone carbonyl data can be used to study electrostatic coupling in proteins and provide specific information on hydrogen bonding and electrostatic potential at nontitrating sites.},
  author       = {Lindman, Stina and Linse, Sara and Mulder, Frans and André, Ingemar},
  issn         = {1542-0086},
  language     = {eng},
  number       = {1},
  pages        = {257--266},
  publisher    = {Cell Press},
  series       = {Biophysical Journal},
  title        = {pK(a) values for side-chain carboxyl groups of a PGB1 variant explain salt and pH-dependent stability},
  url          = {http://dx.doi.org/10.1529/biophysj.106.088682},
  volume       = {92},
  year         = {2007},
}