Thermodynamic Analysis of Myelin Basic Protein Adsorbed on Liquid Crystalline Dioleoylphosphatidylcholine Monolayer
Zhang Lei1, Sun Runguang2, Hao Changchun2
1Department of Experimental Teaching Center for Optoelectronic Science and Information Engineering, Xi'an Aeronautical University, Xi'an, 710077 Shaanxi, China.
Insights
Myelin basic protein (MBP) interacts with unsaturated lipid dioleoylphosphatidylcholine (DOPC) monolayers, altering their stability and dynamics. Increased MBP concentration leads to hydrophobic insertion and surface accumulation, impacting lipid arrangement and conformation.
Area of Science:
- Biophysics
- Materials Science
- Biochemistry
Background:
- Unsaturated lipids like dioleoylphosphatidylcholine (DOPC) are crucial components of cell membranes.
- Myelin basic protein (MBP) plays a role in neurological functions and diseases.
- Understanding lipid-protein interactions is vital for membrane biophysics and disease pathogenesis.
Purpose of the Study:
- To investigate the stability and dynamic characteristics of DOPC monolayers interacting with varying concentrations of MBP.
- To elucidate the mechanism of MBP adsorption and its impact on lipid monolayer structure.
- To quantify the thermodynamic parameters of the MBP-DOPC interaction.
Main Methods:
- Langmuir technique for monolayer characterization.
- Atomic Force Microscopy (AFM) for surface morphology analysis.
- Thermodynamic analysis based on the mass conservation equation.
Main Results:
- Surface pressure-area and surface pressure-time isotherms revealed changes in monolayer physical properties.
- AFM imaging showed increased micro-region expansion with higher MBP concentrations, indicating hydrophobic insertion and surface accumulation.
- The partition coefficient and molecular area of adsorbed MBP were calculated.
Conclusions:
- MBP concentration significantly affects the arrangement and conformation of DOPC monolayers.
- Hydrophobic interactions drive MBP insertion and accumulation on the lipid surface.
- Findings provide insights into biofilm structure, disease pathogenesis, and potential treatments.
Abstract:
To investigate the stability and dynamic characteristics of monolayer adsorbed on unsaturated lipid dioleoylphosphatidylcholine (DOPC) with varying concentrations of myelin basic protein (MBP), the system is studied by applying Langmuir technique and making atomic force microscope (AFM) observation, which is based on the mass conservation equation analysis method referred to in the thermodynamics theory. As indicated by surface pressure-mean molecular area (π - A) and surface pressure-adsorption time (π - T) isotherms, the physical properties of monolayer derived from the interaction of varying concentrations of MBP with liquid crystalline unsaturated lipid DOPC molecules were qualitatively studied. As revealed by surface morphology analysis with AFM, the micro region was expanded as the concentration of MBP in the subphase was on the increase, suggesting that hydrophobic interactions led to the MBP insertion, thus causing accumulation of the MBP on the surface of the monolayer. Experimental results have demonstrated that the partition coefficient of the interaction between MBP and unsaturated phospholipid DOPC and the molecular area of MBP adsorbed on the monolayer film was calculated using the mass conservation equation. In addition, not only does the varying concentration of MBP in the subphase exerts significant effects on the arrangement and conformation of DOPC monolayer, it also has certain guiding significance to exploring the structural changes to biofilm supramolecular aggregates as well as the pathogenesis and treatment of related diseases.
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