Journal of Dairy Research

Table of Contents - May 2012 - Volume 79, Issue 02  

Research Article

Calorimetric and Spectroscopic investigations οf β-lactoglobulin upon interaction with copper ion

Adeleh Divsalara1a2 c1, Sajedeh Ebrahim Damavandia1, Ali Akbar Sabourya1, Arefeh Seyedarabia3 and Ali Akbar Moosavi-Movahedia1

a1 Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran

a2 Department of Biological Sciences, Tarbiat Moallem University, Tehran, Iran

a3 Institute of Structural and Molecular Biology, University College London, London, UK

Abstract

The effect of copper(II) ions (Cu+2) on the structure of β-lactoglobulin (β-lg) was investigated spectroscopically using UV-visible, fluorescence and circular dichroism (CD) and calorimetrically using isothermal titration calorimetry (ITC), at different temperatures. Results of the UV-visible studies showed that adding Cu+2 to β-lg solution caused increasing turbidity, indicative of protein aggregation. It was noticeable that the rate of increasing turbidity was directly proportional to increasing temperature. The far-UV CD studies displayed that the Cu+2 cannot induce any significant changes in the secondary structures of β-lg at different temperatures. Also, the ITC data indicated that the binding process of Cu+2 to β-lg is mainly entropically driven. The results highlight that copper ions cause the tertiary structure of β-lg to change and induce a slightly open structure leading to the formation of supramolecular aggregates in β-lg which may result in the reduced allergenicity of β-lg and its increased use in industrial applications.

(Received December 9 2010)

(Accepted January 5 2012)

(Online publication April 19 2012)

Keywords

Correspondence:

c1 For correspondence; e-mail: divsalar@ibb.ut.ac.ir