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Electrostatic contributions to residue-specific protonation equilibria and proton binding capacitance for a small protein

Lindman, Stina LU ; Linse, Sara LU ; Mulder, Frans LU and André, Ingemar LU orcid (2006) In Biochemistry 45(47). p.13993-14002
Abstract
Charge-charge interactions in proteins are important in a host of biological processes. Here we use C-13 NMR chemical shift data for individual aspartate and glutamate side chain carboxylate groups to accurately detect site-specific protonation equilibria in a variant of the B1 domain of protein G (PGB1-QDD). Carbon chemical shifts are dominated by changes in the electron distribution within the side chain and therefore excellent reporters of the charge state of individual groups, and the data are of high precision. We demonstrate that it is possible to detect local charge interactions within this small protein domain that stretch and skew the chemical shift titration curves away from "ideal" behavior and introduce a framework for the... (More)
Charge-charge interactions in proteins are important in a host of biological processes. Here we use C-13 NMR chemical shift data for individual aspartate and glutamate side chain carboxylate groups to accurately detect site-specific protonation equilibria in a variant of the B1 domain of protein G (PGB1-QDD). Carbon chemical shifts are dominated by changes in the electron distribution within the side chain and therefore excellent reporters of the charge state of individual groups, and the data are of high precision. We demonstrate that it is possible to detect local charge interactions within this small protein domain that stretch and skew the chemical shift titration curves away from "ideal" behavior and introduce a framework for the analysis of such convoluted data to study local charge-charge interactions and electrostatic coupling. It is found that, due to changes in electrostatic potential, the proton binding affinity, K-a, of each carboxyl group changes throughout the titration process and results in a linearly pH dependent pK(a) value. This result could be readily explained by calculations of direct charge-charge interactions based on Coulomb's law. In addition, the slope of pK(a) versus pH was dependent on screening by salt, and this dependence allowed the selective study of charge-charge interactions. For PGB1-QDD, it was established that mainly differences in self-energy, and not direct charge-charge interactions, are responsible for shifted pK(a) values within the protein environment. (Less)
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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
45
issue
47
pages
13993 - 14002
publisher
The American Chemical Society (ACS)
external identifiers
  • wos:000242179100007
  • scopus:33751560650
  • pmid:17115694
ISSN
0006-2960
DOI
10.1021/bi061555v
language
English
LU publication?
yes
id
9c08892a-fa7f-4146-b38d-58773c7b6c00 (old id 376656)
date added to LUP
2016-04-01 12:18:43
date last changed
2021-02-17 02:55:17
@article{9c08892a-fa7f-4146-b38d-58773c7b6c00,
  abstract     = {Charge-charge interactions in proteins are important in a host of biological processes. Here we use C-13 NMR chemical shift data for individual aspartate and glutamate side chain carboxylate groups to accurately detect site-specific protonation equilibria in a variant of the B1 domain of protein G (PGB1-QDD). Carbon chemical shifts are dominated by changes in the electron distribution within the side chain and therefore excellent reporters of the charge state of individual groups, and the data are of high precision. We demonstrate that it is possible to detect local charge interactions within this small protein domain that stretch and skew the chemical shift titration curves away from "ideal" behavior and introduce a framework for the analysis of such convoluted data to study local charge-charge interactions and electrostatic coupling. It is found that, due to changes in electrostatic potential, the proton binding affinity, K-a, of each carboxyl group changes throughout the titration process and results in a linearly pH dependent pK(a) value. This result could be readily explained by calculations of direct charge-charge interactions based on Coulomb's law. In addition, the slope of pK(a) versus pH was dependent on screening by salt, and this dependence allowed the selective study of charge-charge interactions. For PGB1-QDD, it was established that mainly differences in self-energy, and not direct charge-charge interactions, are responsible for shifted pK(a) values within the protein environment.},
  author       = {Lindman, Stina and Linse, Sara and Mulder, Frans and André, Ingemar},
  issn         = {0006-2960},
  language     = {eng},
  number       = {47},
  pages        = {13993--14002},
  publisher    = {The American Chemical Society (ACS)},
  series       = {Biochemistry},
  title        = {Electrostatic contributions to residue-specific protonation equilibria and proton binding capacitance for a small protein},
  url          = {http://dx.doi.org/10.1021/bi061555v},
  doi          = {10.1021/bi061555v},
  volume       = {45},
  year         = {2006},
}