Study Of Phase Behavior Of The Interaction Between The Lysozyme And Anionic Surfactants And Thermal Denaturation Of Lysoyzme

The study of the interactions between proteins and surfactant was important inmany fields such as biology, medicine and cosmetic, moreover, the study of theinteractions between proteins and surfactant can provide valuable model forunderstanding the combining between the protein and molecular such as lipoidcompound or hormone. From the point of view of practical application, protein can keepits activities in the solution of surfanctants. So, the studies of these aspects alwaysflourish. Lysozyme is extensive in diversified biology and animalcule. People appliedthe lysozyme in medical treatment, food antiseptic and biology engineering in the baseof lysozyme's characteristic, especially in food antiseptic.Just because of lysozyme'sextensive being and its application range is wide, it is very necessary to study thethermal denaturation of lysozyme.This work studied the thermal denaturation oflysoyzme and phase behavior of the interaction between the anionic surfactants andlysozyme.The interactions between protein lysozyme and the anionic surfactants werestudied by UV-Vis spectroscopy. The interaction between proteins and anionicsurfactants depends on the protein properties (especially the protein net charge) and thestructure of the anionic surfactants. Different anionic surfactants includingC_nH_2n+1SO₄Na and C_nH_2n+1SO₃Na (n=8,10,12), C_nSO₄ and C_nSO₃ represent sodiumalkyl sulfate and sodium alkyl sulfonate respectively. Lysozyme is positively chargedand has strong interaction with anionic surf actants at pH 7.0. Lysozyme structurechanged in C_nSO_4/3-rich C_nSO_4/3-lysozyme mixtures. The result indicates that thesodium alkyl sulfate has stronger interaction with lysozyme than the sodium alkylsulfonate at the same hydrocarbon chain length. While the interactions between anionicsurfactants and lysozyme became stronger with the increase of the hydrocarbon chainlength at the same head group. The interaction became weaker when the saltconcentration ranged from 0 mmol/L to 50 mmol/L. When it was increased to 100mmol/L, the interaction was enhanced.The interactions between lysozyme and anionicsurfactants.The relation between the thermal denatutation of lysozyme and the anionicsurfactants was studied by UV-Vis spectroscopy and CD. Lysozyme, which is a very stable protein, has very weak change when the pH value ranged from 1.2 to 11.3. Butwe found that some anionic surfactants can accelerate, restrain or maintain the thermaldenaturation of lysozyme in certain concentration. The thermal denaturation oflysozyme became stronger when the concentration of C₈SO₄ ranged from 1mmol/L to0.25mmol/L and the concentration of C₈SO₃ was 10mmol/L. The temperature of thermaldenaturation of lysozyme changed from 34gK to 343K. While it maintain thetemperature of thermal denaturation was 348K when the concentration of C₈SO₃ rangedfrom 5mmol/L to 1mmol/L, the concentration of C₁₀SO₄ ranged from 0.3mmol/L to0.1 mmol/L, the concentration of C₁₀SO₃ ranged from 0.5mmol/L to 0.05mmol/L exceptthe concentration of 0.25mmol/L. When the concentration of C₁₀SO₄ from 0.5mmol/Lto 0.025mmol/L, the concentration of C₁₀SO₃ was 0.25mmol/L, the concentration ofC₁₂SO₄ was ragede from 0.03mmol/L to 0.0025mmol/L and the concentration of C₁₂SO₃was ragede from 0.04mmol/L to 0.005mmol/L, the temperature of the thermaldenaturation of lysozyme changed from 348K to 353K. We can choose some anionicsurfactants which had certain concentration to control the temperature of the thermaldenaturation of lyaozyme. So we can extend the application area of lysozyme inpractical and daily life.