Effect of Starch on the Thermal, Kinetics, and Transmittance Properties of Lysozyme

摘要

The effect of starch fractions added to lysozyme in aqueous solutions was estimated byrndifferential scanning calorimetry (DSC), kinetics, and transmittance turbidometry. Lysozymernwas unfolded and folded five times in the presence of starch fractions. Overall, a trend of higherrnTo values during the unfolding process was observed with the 2% addition of all starch fractionsrnexcept amylose. The effect of starch and starch fractions on lysozyme unfolding and foldingrncycles showed variations based on the MW of the interacting fraction. The increase in thernnumber of cycles influenced the effect of starch on lysozyme denaturation. The percentage ofrnlysozyme's △H values decreased as a new heating and cooling cycle was performed (i.e., 74.4%rnof the △H remained from the first cycle). The effect of amylose (AM)and amylopectin (AP) on rnthe kinetics of lysozyme unfolding and folding was found to be different based on thernassumption that the peak DSC temperature is the fastest step of the reaction. The unfoldingrnshowed higher activation energy (Ea) in the presence of both AM and AP, while the folding wasrnnot significantly changed. The turbidity of the solution containing lysozyme and potato starchrnshowed transmittance in between the lysozyme and starch. Stirring of the blend kept therntransmittance unchanged while an increase in the transmittance was noticed when stirring seized.