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Thermodynamic insights into the binding of triton X-100 to globular proteins: A calorimetric and spectroscopic investigation

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Title Thermodynamic insights into the binding of triton X-100 to globular proteins: A calorimetric and spectroscopic investigation
 
Creator SINGH, SK
KISHORE, N
 
Subject bovine serum-albumin
alpha-lactalbumin
ionic surfactants
crystal-structure
ligand-binding
high-pressure
interface
deoxycholate
purification
micelles
 
Description The interaction of the nonionic surfactant Triton X-100 (TX-100) with two proteins ( bovine serum albumin (BSA) and R-lactalbumin (R-LA)) has been investigated by using a combination of differential scanning calorimetry, isothermal titration calorimetry, and fluorescence and circular dichroism spectroscopies. All of the calorimetric transitions in BSA were partially reversible, while being two-state and reversible in the case of R-LA. TX-100 molecules do not reduce the thermal stability of the protein in the monomeric form. However, in the micellar form the protein might become thermally destabilized by the micelles depending upon the nature of the protein. Isothermal titration calorimetry has been used to demonstrate that TX-100 binds to BSA at two sets of sites with 4: 1 stoichiometry in each case. The van't Hoff enthalpy calculated from the temperature dependence of the binding constant did not match with the calorimetric enthalpy indicating conformational change in the protein upon surfactant binding. The surfactant binds to R-LA with one class of binding site, and the thermal unfolding results indicate it to be a stronger destabilizer than BSA. The fluorescence, circular dichroism, and differential scanning calorimetric results corroborate well with each other. The effect of ionic strength on the binding parameters suggests that TX-100 can bind to the protein surface via both hydrophobic and polar interactions depending upon the nature of the protein. The physical chemistry underlying the interactions between TX-100 and proteins has been presented. The mode of interaction of TX-100 with proteins is via direct binding, which has been discussed quantitatively in this work.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-07-15T02:41:05Z
2011-12-26T12:49:11Z
2011-12-27T05:34:59Z
2011-07-15T02:41:05Z
2011-12-26T12:49:11Z
2011-12-27T05:34:59Z
2006
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY B, 110(19), 9728-9737
1520-6106
http://dx.doi.org/10.1021/jp0608426
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4131
http://hdl.handle.net/10054/4131
 
Language en