Why can hydrogen sulfide permeate cell membranes?

Area of Science:

• Biophysics
• Computational Chemistry
• Membrane Science

Background:

• Cellular membranes control the passage of molecules.
• Hydrogen sulfide (H2S) is a biologically relevant gas with known signaling roles.
• Understanding H2S transport across membranes is crucial for cell physiology.

Purpose of the Study:

• To investigate the molecular mechanisms underlying the high membrane permeability of H2S.
• To quantify the permeation of H2S across a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer.
• To compare the transport properties of H2S with water (H2O) within a lipid bilayer environment.

Main Methods:

• Utilizing polarizable molecular dynamics (MD) simulations.
• Employing a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer model.
• Applying the solubility-diffusion model to predict permeability coefficients.

Main Results:

• MD simulations accurately predicted H2S and H2O permeability coefficients, matching experimental data.
• H2S demonstrated a lower diffusion coefficient compared to H2O within the membrane.
• The Gibbs energy profile revealed a negligible energetic barrier for H2S permeation.
• The hydrophobicity of H2S facilitates its ready partitioning into the membrane's hydrophobic core.

Conclusions:

• H2S readily permeates lipid bilayers, primarily driven by its hydrophobic nature.
• Computational simulations provide a reliable method for studying gas transport across membranes.
• The findings support the role of H2S as a membrane-permeant signaling molecule.