Spin Relaxation Does Not Preclude Magnetic Field Effects on Lipid Autoxidation

Area of Science:

• Biophysics
• Chemical Physics
• Computational Biology

Background:

• Spin correlations are crucial for biological processes, with spin relaxation dictating their decay.
• Magnetic field effects (MFEs) in lipid autoxidation are proposed to originate from lipid peroxide radicals, but rapid membrane relaxation raises questions about their persistence.
• Understanding spin dynamics in membranes is vital for elucidating biological mechanisms and disease pathologies.

Purpose of the Study:

• To investigate the persistence of MFEs in lipid bilayers despite spin relaxation.
• To identify the key molecular dynamics and interactions driving spin relaxation in lipid peroxide radicals within membranes.
• To explore the influence of magnetic field strength on MFEs in biological membranes.

Main Methods:

• All-atom molecular dynamics (MD) simulations of a palmitoyl-linoleoyl-phosphatidylcholine (PLPC) model membrane with lipid peroxide radicals.
• Density functional theory (DFT) calculations to determine g-tensors and hyperfine coupling constants.
• Spin dynamics modeling incorporating MD-derived fluctuations and Bloch-Redfield-Wangsness relaxation theory.

Main Results:

• Peroxide group rotation and lipid backbone dynamics were identified as primary drivers of spin relaxation.
• Spin relaxation is dominated by g-fluctuations, which surprisingly enhance MFEs at both high and weak magnetic fields.
• MFEs were demonstrated to persist in lipid bilayers despite significant thermal motion and relaxation effects.

Conclusions:

• MFEs can persist in lipid bilayers, contrary to previous assumptions, due to specific molecular dynamics.
• G-fluctuations play a critical role in modulating MFEs, enhancing them across a range of magnetic field strengths.
• These findings have significant implications for understanding biological MFEs and their roles in ferroptosis, cancer, and oxidative stress-related diseases.