Thermodynamic Analysis of Myelin Basic Protein Adsorbed on Liquid Crystalline Dioleoylphosphatidylcholine Monolayer.

Zhang Lei,Yang Huihui,Hao Changchun,Hu Chengxi,Sun Runguang

doi:10.1155/2019/8175413

Zhang Lei, Yang Huihui + Show 3 more

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https://doi.org/10.1155/2019/8175413

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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.

Highlights

The myelin is an asymmetric multilamellar membrane structure derived from oligodendrocytes present in the central nervous system (CNS)
Our results revealed the quantitative relationship between myelin basic protein (MBP) and unsaturated lipid DOPC molecules and the adsorption kinetics of protein molecules onto DOPC monolayers were quantitatively analyzed using thermodynamic method
The results obtained from the experimental demonstrate that (1) we have succeeded in applying mathematical and physical methods to determine a possible adsorption of MBP in the DOPC monolayer

Summary

Introduction

The myelin is an asymmetric multilamellar membrane structure derived from oligodendrocytes present in the central nervous system (CNS). As indicated by the results of biochemical molecular test, the structure of myelin sheath membrane is primarily a compact stack of lipid bilayers (mainly phospholipids), sphingolipid (mainly galactose brain glycosides), and proteins, as shown in Figure 1 [1,2,3,4]. The interaction of MBP with different lipids has long been studied, such as the acidic lipids and neutral lipids, the quantitative study on the interaction between unsaturated lipid dioleoylphosphatidylcholine (DOPC) and myelin basic protein (MBP) remains excluded from discussion. Three amphipathic α-helices are present in proteins that bind to the myelin sheath, which are located at the N- and C-termini and in the central region.

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