Author
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Mohamed, Abdellatif |
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Submitted to: North American Thermal Analysis Society Meeting
Publication Type: Abstract Only Publication Acceptance Date: 5/1/2003 Publication Date: 9/24/2003 Citation: Mohamed, A. 2003. Thermal stability and folding kinetics of lysozyme [abstract]. North American Thermal Analysis Society Meeting. p.29. Interpretive Summary: Technical Abstract: A number of researchers reported linear correlations between lysozyme denaturation temperatures and the folding rate in the presence of different organic solvents and various levels of pH and ionic strength. This work is focused on determining the kinetics of lysozyme folding in the presence of amylose and amylopectin using DSC. Lysozyme solution, 100 mg / ml, was heated to 90ºC, held at temperature for 1 min, cooled to 20ºC, and held at temperature for 1 min. Five cycles of heating and cooling were performed. Samples were heated at a 1, 3, 5, 7, 9, and 11ºC / min heating rate. Pure lysozyme showed higher onset, and peak temperatures during the unfolding (heating) step as the heating rate increased, while during the folding process (cooling) these temperatures were lower. The delta-H of unfolding showed lower values during unfolding and higher values during folding as the heating rate increased. Lysozyme protein did not fold at 1 and 3ºC / min cooling rate. The activation energy (Ea) was calculated based on the assumption that the peak temperature of lysozyme changed with the heating rate. The Ea showed increase at higher amylopectin concentration during unfolding while the folding process was not affected by addition of amylopectin. At 1% amylose Ea during the unfolding has increased and was slightly higher upon folding, where at 2% amylose the Ea was unchanged. Change in the Ea during the folding-unfolding of lysozyme is indicative of stronger interaction with amylopectin. |
