Interaction of lysozyme with negatively charged flexible chain polymers.
The complex formation between the basic protein lysozyme and anionic polyelectrolytes: poly acrylic acid and poly vinyl sulfonic acid was studied by turbidimetric and isothermal calorimetric titrations. The thermodynamic stability of the protein in the presence of these polymers was also studied by differential scanning calorimetry. The lysozyme-polymer complex was insoluble at pH lower than 6, with a stoichiometric ratio (polymer per protein mol) of 0.025-0.060 for lysozyme-poly vinyl sulfonic acid and around 0.003-0.001 for the lysozyme-poly acrylic acid. NaCl 0.1M inhibited the complex precipitation in agreement with the proposed coulombic mechanism of complex formation. Enthalpic and entropic changes associated to the complex formation showed highly negative values in accordance with a coulombic interaction mechanism. The protein tertiary structure and its thermodynamic stability were not affected by the presence of polyelectrolyte.
Romanini
Diana
D
Bioseparation Lab, Physical-Chemistry Department, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, FonCyT, CIUNR and CONICET, Suipacha 570, S2002RLK, Rosario, Argentina. dianaromanini@hotmail.com
Braia
Mauricio
M
Angarten
Rodrigo Giatte
RG
Loh
Watson
W
Picó
Guillermo
G
D000179:Acrylates / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D011232:Chemical Precipitation; D004527:Egg Proteins / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D009391:Nephelometry and Turbidimetry; D011092:Polyethylene Glycols / Q000737:chemistry; D011100:Polyglycolic Acid / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry; D011485:Protein Binding; D012995:Solubility / Q000187:drug effects; D013816:Thermodynamics
D000179:Acrylates; D004527:Egg Proteins; D046911:Macromolecular Substances; D011108:Polymers; D011145:Polyvinyls; D011100:Polyglycolic Acid; D011092:Polyethylene Glycols; D009113:Muramidase; C036658:acrylic acid