Modeling order-disorder transition in Low-Density Lipoprotein.

Area of Science:

• Biophysics
• Computational Chemistry
• Materials Science

Background:

• Low Density Lipoproteins (LDL) are crucial for lipid transport.
• LDL particles contain cholesteryl esters (CE) in their core.
• CE undergoes a reversible thermal transition near physiological temperatures.

Purpose of the Study:

• To model the order-disorder thermal transition of cholesteryl esters in LDL.
• To investigate the role of chain-chain interactions in CE phase stability.
• To simulate the melting process and obtain the heat capacity curve.

Main Methods:

• Formulation of a coarse-grained two-state model for CE melting.
• Inclusion of nearest neighbor interactions only.
• Metropolis Monte Carlo (MC) simulations were performed.

Main Results:

• The simulation successfully modeled the cooperative melting of CE.
• The heat capacity curve revealed characteristic features of finite-size systems.
• Chain-chain interactions were identified as key to the smectic phase stability.

Conclusions:

• A simplified model effectively captures the thermal transition of CE in LDL.
• Monte Carlo simulations provide insights into the physical mechanisms of LDL core melting.
• Understanding this transition is vital for LDL particle stability and function.