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Osmotically unresponsive water fraction on proteins: Non‐ideal osmotic pressure of bovine serum albumin as a function of pH and salt concentration
Author(s) -
Fullerton Gary D.,
Kanal Kalpana M.,
Cameron Ivan L.
Publication year - 2006
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1016/j.cellbi.2005.11.001
Subject(s) - bovine serum albumin , chemistry , osmotic pressure , salt (chemistry) , globular protein , freezing point , chromatography , molecular mass , osmosis , membrane , albumin , serum albumin , biophysics , biochemistry , thermodynamics , organic chemistry , enzyme , physics , biology
How much does protein‐associated water differ in colligative properties (freezing point, boiling point, vapor pressure and osmotic behavior) from pure bulk water? This question was approached by studying the globular protein bovine serum albumin (BSA), using changes in pH and salt concentration to alter its native structural conformation and state of aggregation. BSA osmotic pressure was investigated experimentally and analyzed using the molecular model of Fullerton et al. [Biochem Cell Biol 1992;70(12):1325]. Analysis yielded both the extent of osmotically unresponsive water (OUW) and the effective molecular weight values of the membrane‐impermeable BSA solute. Manipulation of BSA conformation and aggregation by membrane‐penetrating cosolutes show that alterations in pH and salt concentration change the amount of bulk water that escapes into BSA from a minimum of 1.4 to a maximum of 11.7 g water per g dry mass BSA.