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Protein self-association in solution: the bovine pancreatic trypsin inhibitor decamer.

Gottschalk, Michael LU ; Venu, Kandadai and Halle, Bertil LU (2003) In Biophysical Journal 84(6). p.3941-3958
Abstract
We have used magnetic relaxation dispersion to study bovine pancreatic trypsin inhibitor (BPTI) self-association as a function of pH, salt type and concentration, and temperature. The magnetic relaxation dispersion method sensitively detects stable oligomers without being affected by other interactions. We find that BPTI decamers form cooperatively under a wide range of solution conditions with no sign of dimers or other small oligomers. Decamer formation is opposed by electrostatic repulsion among numerous cationic residues confined within a narrow channel. Accordingly, the decamer population increases with increasing pH, as cationic residues are deprotonated, and with increasing salt concentration. The salt effect cannot be described in... (More)
We have used magnetic relaxation dispersion to study bovine pancreatic trypsin inhibitor (BPTI) self-association as a function of pH, salt type and concentration, and temperature. The magnetic relaxation dispersion method sensitively detects stable oligomers without being affected by other interactions. We find that BPTI decamers form cooperatively under a wide range of solution conditions with no sign of dimers or other small oligomers. Decamer formation is opposed by electrostatic repulsion among numerous cationic residues confined within a narrow channel. Accordingly, the decamer population increases with increasing pH, as cationic residues are deprotonated, and with increasing salt concentration. The salt effect cannot be described in terms of Debye screening, but involves the ion-specific sequestering of anions within the narrow channel. The lifetime of the BPTI decamer is 101 ± 4 min at 27°C. We propose that the BPTI decamer, with a heparin chain threading the decamer channel, plays a functional role in the mast cell. We also detect a higher oligomer that appears to be a subcritical nucleation cluster of 3–5 decamers. We argue that monomeric crystals form at high pH despite a high decamer population in solution, because the ion pairs that provide the critical decamer-decamer contacts are disrupted at high pH. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
84
issue
6
pages
3941 - 3958
publisher
Cell Press
external identifiers
  • pmid:12770900
  • wos:000183129800040
  • scopus:0038693409
ISSN
1542-0086
language
English
LU publication?
yes
id
c53dd7c4-94cd-4e71-8aa9-9617856d0ff0 (old id 128040)
alternative location
http://www.pubmedcentral.gov/articlerender.fcgi?artid=1302976&rendertype=abstract
http://www.biophysj.org/cgi/content/abstract/84/6/3941
date added to LUP
2007-06-29 09:55:44
date last changed
2017-07-02 03:28:17
@article{c53dd7c4-94cd-4e71-8aa9-9617856d0ff0,
  abstract     = {We have used magnetic relaxation dispersion to study bovine pancreatic trypsin inhibitor (BPTI) self-association as a function of pH, salt type and concentration, and temperature. The magnetic relaxation dispersion method sensitively detects stable oligomers without being affected by other interactions. We find that BPTI decamers form cooperatively under a wide range of solution conditions with no sign of dimers or other small oligomers. Decamer formation is opposed by electrostatic repulsion among numerous cationic residues confined within a narrow channel. Accordingly, the decamer population increases with increasing pH, as cationic residues are deprotonated, and with increasing salt concentration. The salt effect cannot be described in terms of Debye screening, but involves the ion-specific sequestering of anions within the narrow channel. The lifetime of the BPTI decamer is 101 ± 4 min at 27°C. We propose that the BPTI decamer, with a heparin chain threading the decamer channel, plays a functional role in the mast cell. We also detect a higher oligomer that appears to be a subcritical nucleation cluster of 3–5 decamers. We argue that monomeric crystals form at high pH despite a high decamer population in solution, because the ion pairs that provide the critical decamer-decamer contacts are disrupted at high pH.},
  author       = {Gottschalk, Michael and Venu, Kandadai and Halle, Bertil},
  issn         = {1542-0086},
  language     = {eng},
  number       = {6},
  pages        = {3941--3958},
  publisher    = {Cell Press},
  series       = {Biophysical Journal},
  title        = {Protein self-association in solution: the bovine pancreatic trypsin inhibitor decamer.},
  volume       = {84},
  year         = {2003},
}