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Solubility of Globular Proteins in Polysaccharide Solutions
Author(s) -
Guo Meining,
Narsimhan Ganesan
Publication year - 1991
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp00007a009
Subject(s) - polysaccharide , globular protein , lysozyme , dextran , solubility , chemistry , isoelectric point , ovalbumin , molecule , chromatography , crystallography , organic chemistry , biochemistry , biology , enzyme , immune system , immunology
A statistical thermodynamic model based on the lattice model proposed by Baskir et al. (1987) was employed to predict the solubilities of globular proteins such as ovalbumin and lysozyme at their isoelectric points in dextran solutions of different molecular weights. The model accounted for protein‐polysaccharide and polysaccharide‐solvent interactions as well as entropy of mixing, and it employed simplifying assumptions such as a linear homogeneous polysaccharide molecule and a spherical globular protein molecule of uniform surface properties. The protein‐polysaccharide interaction parameter χs, obtained by fitting the model to experimental data for one molecular weight of dextran, was found to be 0.132 and 0.115 for ovalbumin and lysozyme, respectively. Solubilities of ovalbumin and lysozyme in dextran solutions of different molecular weights exhibited a shallow maximum at intermediate dextran concentrations and compared well with model predictions. Protein solubility was found to be very sensitive to protein‐polysaccharide interactions and increase with more favorable protein‐polysaccharide interactions (larger χs), less favorable polysaccharide‐solvent interactions (larger χ), smaller size protein molecule, and lower molecular weight polysaccharide.