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Reentrant Phase Behavior in Protein Solutions Induced by Multivalent Salts: Strong Effect of Anions Cl– Versus NO3–

Braun, Michal K. ; Sauter, Andrea ; Matsarskaia, Olga ; Wolf, Marcell ; Roosen-Runge, Felix LU ; Sztucki, Michael ; Roth, Roland ; Zhang, Fajun and Schreiber, Frank (2018) In The Journal of Physical Chemistry Part B 122(50). p.11978-11985
Abstract
In this work, the effects of the two anions Cl– and NO3– on the phase behavior of bovine serum albumin (BSA) in solution with trivalent salts are compared systematically. In the presence of trivalent metal salts, negatively charged proteins such as BSA in solution undergo a reentrant condensation (RC) phase behavior, which has been established for several proteins with chlorides of trivalent salts. Here, we show that replacing Cl– by NO3– leads to a marked change in the phase behavior. The effect is investigated for the two different cations Y3+ and La3+. The salts are thus YCl3, Y(NO3)3, LaCl3, and La(NO3)3. The experimental phase behavior shows that while the chloride salts induce both liquid–liquid phase separation (LLPS) and RC, the... (More)
In this work, the effects of the two anions Cl– and NO3– on the phase behavior of bovine serum albumin (BSA) in solution with trivalent salts are compared systematically. In the presence of trivalent metal salts, negatively charged proteins such as BSA in solution undergo a reentrant condensation (RC) phase behavior, which has been established for several proteins with chlorides of trivalent salts. Here, we show that replacing Cl– by NO3– leads to a marked change in the phase behavior. The effect is investigated for the two different cations Y3+ and La3+. The salts are thus YCl3, Y(NO3)3, LaCl3, and La(NO3)3. The experimental phase behavior shows that while the chloride salts induce both liquid–liquid phase separation (LLPS) and RC, the nitrate salts also induce LLPS, but RC becomes partial with La(NO3)3 and disappears with Y(NO3)3. The observed phase behavior is rationalized by effective protein–protein interactions which are characterized using small-angle X-ray scattering. The results based on the reduced second virial coefficients B2/B2HS and 1/I(q → 0) demonstrate that the NO3– salts induce a stronger attraction than the Cl– salts. Overall, the effective attraction, the width of the condensed regime in the RC phase diagram, and the nature of LLPS follow the order LaCl3 < YCl3 < La(NO3)3 < Y(NO3)3. Despite the decisive role of cations in RC phase behavior, isothermal titration calorimetry measurements indicate that replacing anions does not significantly influence the cation binding to proteins. The experimental results observed are discussed based on an “enhanced Hofmeister effect” including electrostatic and hydrophobic interactions between protein–cation complexes. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
122
issue
50
pages
11978 - 11985
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:30461282
  • scopus:85058508302
ISSN
1520-5207
DOI
10.1021/acs.jpcb.8b10268
language
English
LU publication?
yes
id
397586c1-2203-4ec7-b1c9-bf335d672cb8
date added to LUP
2018-12-17 09:59:46
date last changed
2022-04-25 19:51:09
@article{397586c1-2203-4ec7-b1c9-bf335d672cb8,
  abstract     = {{In this work, the effects of the two anions Cl– and NO3– on the phase behavior of bovine serum albumin (BSA) in solution with trivalent salts are compared systematically. In the presence of trivalent metal salts, negatively charged proteins such as BSA in solution undergo a reentrant condensation (RC) phase behavior, which has been established for several proteins with chlorides of trivalent salts. Here, we show that replacing Cl– by NO3– leads to a marked change in the phase behavior. The effect is investigated for the two different cations Y3+ and La3+. The salts are thus YCl3, Y(NO3)3, LaCl3, and La(NO3)3. The experimental phase behavior shows that while the chloride salts induce both liquid–liquid phase separation (LLPS) and RC, the nitrate salts also induce LLPS, but RC becomes partial with La(NO3)3 and disappears with Y(NO3)3. The observed phase behavior is rationalized by effective protein–protein interactions which are characterized using small-angle X-ray scattering. The results based on the reduced second virial coefficients B2/B2HS and 1/I(q → 0) demonstrate that the NO3– salts induce a stronger attraction than the Cl– salts. Overall, the effective attraction, the width of the condensed regime in the RC phase diagram, and the nature of LLPS follow the order LaCl3 &lt; YCl3 &lt; La(NO3)3 &lt; Y(NO3)3. Despite the decisive role of cations in RC phase behavior, isothermal titration calorimetry measurements indicate that replacing anions does not significantly influence the cation binding to proteins. The experimental results observed are discussed based on an “enhanced Hofmeister effect” including electrostatic and hydrophobic interactions between protein–cation complexes.}},
  author       = {{Braun, Michal K. and Sauter, Andrea and Matsarskaia, Olga and Wolf, Marcell and Roosen-Runge, Felix and Sztucki, Michael and Roth, Roland and Zhang, Fajun and Schreiber, Frank}},
  issn         = {{1520-5207}},
  language     = {{eng}},
  number       = {{50}},
  pages        = {{11978--11985}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{The Journal of Physical Chemistry Part B}},
  title        = {{Reentrant Phase Behavior in Protein Solutions Induced by Multivalent Salts: Strong Effect of Anions Cl– Versus NO3–}},
  url          = {{http://dx.doi.org/10.1021/acs.jpcb.8b10268}},
  doi          = {{10.1021/acs.jpcb.8b10268}},
  volume       = {{122}},
  year         = {{2018}},
}