|M.Sc Student||Merav Kimeldorf|
|Subject||The Effect of Underwater Shock Waves on the Properties of|
|Department||Department of Biotechnology and Food Engineering||Supervisor||Ms. Zuckerman Hadassa|
Solutions of b-lactoglobulin (b-LG) were treated with underwater high-current discharges (UHCD) using a bench top system constructed in our laboratory. The short time duration of the UHCD and the high energy delivered to the discharge produced strong shock waves, in a nanosecond time scale, as well as a powerful flash of light with a broad spectrum, ranging from soft x-rays to IR. Structural changes in b-LG were evaluated using hydrophobicity fluorescence of the b-LG molecule, differential scanning calorimetry, reactivity of the free thiol group to Ellman’s reagent, small angle x-ray scattering (SAXS) and circular dichroism (CD). The results indicated that the application of the UHCD to b-LG leads to the increase of its surface hydrophobicity by about 40%. The enthalpy (DHUHCD) of UHCD treated samples decreased as much as 40% compared to the enthalpy (DHnative) of native untreated proteins, indicating extensive but incomplete unfolding of the protein structure with no aggregation. It was found that no refolding occurred after the UHCD treatment. Also, it was shown that the reactivity of the free thiol group of UHCD treated samples increased 10 fold. Tryptophan residues in b-LG were markedly modified, as observed by UV absorption, indicating a change in its position. CD spectra indicated slight modifications in both secondary and tertiary structure. The observed structural changes can be expected to affect the functionality of proteins in a favorable manner.