Response of Ovalbumin to Fructose Addition and pH Variations - Ultrasonic and FTIR Study

Abstract

Main aim of this work is to understand how the protein ovalbumin is affected by the presence of cosolvent and variations in pH of the medium.  The addition of cosolvent in many cases is found to control the extent of denaturation and pH is one of the main sources of denaturant of proteins.  In this work, keeping fructose solution as cosolvent and pH of the solution as main variable, the extent of denaturation is analysed by ultrasonic methods and are further confirmed by FTIR amide-I second derivative spectra at 303 K. Obtained results shows that denaturation is sensitive to pH, however, acidic and alkaline behave totally in a different way.  It was found that the impact of alkaline pH produces lesser denaturation and is slower whereas the impact of acidic pH is specific and instantaneous. Ultrasonic analysis shows that pH variation can denature the protein whereas the addition of cosolvent supports renaturation. FTIR spectra were recorded for the experimental samples from which the second derivative curve fitted spectra were constructed using Origin program.  Quantitative assignment of peaks and the variations in cumulative areas calculated for the structures like α-helix, β-sheets etc confirms the observations of ultrasonic analysis that the pH variations aid in denaturation whereas the cosolvent supports the renaturation of protein.