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Non‐monotonic course of protein solubility in aqueous polymer‐salt solutions can be modeled using the sol‐mxDLVO model
Author(s) -
Herhut Marcel,
Brandenbusch Christoph,
Sadowski Gabriele
Publication year - 2016
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.201500123
Subject(s) - solubility , polyethylene glycol , polymer , aqueous solution , salt (chemistry) , salting out , chemistry , crystallization , lysozyme , urea , chromatography , chemical engineering , materials science , organic chemistry , biochemistry , engineering
Protein purification is often performed using cost‐intensive chromatographic steps. To discover economic alternatives (e.g., crystallization), knowledge on protein solubility as a function of temperature, pH, and additives in solution as well as their concentration is required. State‐of‐the‐art models for predicting protein solubility almost exclusively consider aqueous salt systems, whereas ”salting‐in“ and ”salting‐out“ effects induced by the presence of an additional polymer are not considered. Thus, we developed the sol‐mxDLVO model. Using this newly developed model, protein solubility in the presence of one salt and one polymer, especially the non‐monotonic course of protein solubility, could be predicted. Systems considered included salts (NaCl, Na‐p‐Ts, (NH 4 ) 2 SO 4 ) and the polymer polyethylene glycol (MW: 2000 g/mol, 12000 g/mol) and proteins lysozyme from chicken egg white (pH 4 to 5.5) and D‐xylose ketol‐isomerase (pH 7) at 298.15 K. The results show that by using the sol‐mxDLVO model, protein solubility in polymer‐salt solutions can be modeled in good agreement with the experimental data for both proteins considered. The sol‐mxDLVO model can describe the non‐monotonic course of protein solubility as a function of polymer concentration and salt concentration, previously not covered by state‐of‐the‐art models.