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Time-Dependent pH Scanning of the Acid-Induced Unfolding of Human Serum Albumin Reveals Stabilization of the Native Form by Palmitic Acid Binding

Del Giudice, Alessandra; Dicko, Cedric LU ; Galantini, Luciano and Pavel, Nicolae V. (2017) In Journal of Physical Chemistry B 121(17). p.4388-4399
Abstract

The most abundant plasma protein, human serum albumin (HSA), is known to undergo several conformational transitions in an acidic environment. To avoid buffer effects and correlate global and local structural changes, we developed a continuous acidification method and simultaneously monitored the protein changes by both small-angle scattering (SAXS) and fluorescence. The progressive acidification, based on the hydrolysis of glucono-δ-lactone from pH 7 to pH 2.5, highlighted a multistep unfolding involving the putative F form (pH 4) and an extended and flexible conformation (pH < 3.5). The scattering profile of the F form was extracted by component analysis and further 3D modeled. The effect of acid unfolding at this intermediate stage... (More)

The most abundant plasma protein, human serum albumin (HSA), is known to undergo several conformational transitions in an acidic environment. To avoid buffer effects and correlate global and local structural changes, we developed a continuous acidification method and simultaneously monitored the protein changes by both small-angle scattering (SAXS) and fluorescence. The progressive acidification, based on the hydrolysis of glucono-δ-lactone from pH 7 to pH 2.5, highlighted a multistep unfolding involving the putative F form (pH 4) and an extended and flexible conformation (pH < 3.5). The scattering profile of the F form was extracted by component analysis and further 3D modeled. The effect of acid unfolding at this intermediate stage was assigned to the rearrangement of the three albumin domains drifting apart toward a more elongated conformation, with a partial unfolding of one of the outer domains. To test the stabilizing effect of fatty acids, here palmitic acid, we compared the acid unfolding process of albumin with and without ligand. We found that when binding the ligand, the native conformation was favored up to lower pH values. Our approach solved the problem of realizing a continuous, homogeneous, and tunable acidification with simultaneous characterization applicable to study processes triggered by a pH decrease.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry B
volume
121
issue
17
pages
12 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85020193318
  • wos:000400881300007
ISSN
1520-6106
DOI
10.1021/acs.jpcb.7b01342
language
English
LU publication?
yes
id
dbbf17a1-d47b-4a00-bd0f-32344d6f78de
date added to LUP
2017-06-28 10:48:00
date last changed
2017-09-18 11:43:27
@article{dbbf17a1-d47b-4a00-bd0f-32344d6f78de,
  abstract     = {<p>The most abundant plasma protein, human serum albumin (HSA), is known to undergo several conformational transitions in an acidic environment. To avoid buffer effects and correlate global and local structural changes, we developed a continuous acidification method and simultaneously monitored the protein changes by both small-angle scattering (SAXS) and fluorescence. The progressive acidification, based on the hydrolysis of glucono-δ-lactone from pH 7 to pH 2.5, highlighted a multistep unfolding involving the putative F form (pH 4) and an extended and flexible conformation (pH &lt; 3.5). The scattering profile of the F form was extracted by component analysis and further 3D modeled. The effect of acid unfolding at this intermediate stage was assigned to the rearrangement of the three albumin domains drifting apart toward a more elongated conformation, with a partial unfolding of one of the outer domains. To test the stabilizing effect of fatty acids, here palmitic acid, we compared the acid unfolding process of albumin with and without ligand. We found that when binding the ligand, the native conformation was favored up to lower pH values. Our approach solved the problem of realizing a continuous, homogeneous, and tunable acidification with simultaneous characterization applicable to study processes triggered by a pH decrease.</p>},
  author       = {Del Giudice, Alessandra and Dicko, Cedric and Galantini, Luciano and Pavel, Nicolae V.},
  issn         = {1520-6106},
  language     = {eng},
  month        = {05},
  number       = {17},
  pages        = {4388--4399},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry B},
  title        = {Time-Dependent pH Scanning of the Acid-Induced Unfolding of Human Serum Albumin Reveals Stabilization of the Native Form by Palmitic Acid Binding},
  url          = {http://dx.doi.org/10.1021/acs.jpcb.7b01342},
  volume       = {121},
  year         = {2017},
}