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Please use this identifier to cite or link to this item: http://eprint.iitd.ac.in/handle/2074/275

Title: Differential scanning calorimetricstudies on the effect of ammonium and tetraalkylammonium halides on the stability of lysozyme
Authors: Jain, Sandhya
Ahluwalia, J C
Keywords: Protein stability
Hydrophobic effect
Thermodynamics
Calorimetry
Lysozyme
Tetraalkylammonium halides
Issue Date: 1996
Publisher: Elsevier Science
Citation: Biophysical Chemistry 59 ,171 - 177
Abstract: The thermal denaturation of lysozyme was studied at pH 2.50 and 6.00 in aqueous solutions of ammonium (NH,CI and NH,Br) and tetraalkylammonium halides (Me,NCl, Me,NBr, Et,NBr, Pr,NBr, Bu,NBr) using high-sensitivity differential scanning calorimetry. The ransition temperature, heat capacity, enthalpy, entropy and free energy of denaturation have been determined by a least-squares fit of the excess heat capacity data to the two-state model. Ammonium and tetraalkylammo- nium halides (except Me,NCl and NH&l at high concentrations at pH 6.00) are found to destabilize lysozyme and the destabilization increases with increasing concentration and alkyl chain length. However, NH&l and Me,NCI act as stabilizers at high concentrations at pH 6.00. Results are discussed in terms of electrostatic and hydrophobic interactions. The stabilization of lysozyme by NH&l and Me,NCI can be attributed to the charge on the quatemary nitrogen atom while destabilization in tetraalkylammonium halides solution is due to the interaction between hydrophobic molecules of the medium and the hydrophobic parts of the protein.
URI: http://eprint.iitd.ac.in/dspace/handle/2074/275
Appears in Collections:Chemistry

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