Proton Conduction in Gly-X (X = Ser, Ser-Gly-Ser) and GS50

Area of Science:

• Biomaterials science
• Biophysics
• Materials chemistry

Background:

• Biomaterials are increasingly vital for biocompatible electronic devices.
• Understanding proton conduction mechanisms in peptides is crucial for advanced applications.

Purpose of the Study:

• To investigate the proton conductivity of Glycyl-L-serine (Gly-Ser) in relation to hydration.
• To elucidate the role of hydration water and hydrogen bond networks in peptide proton transport.

Main Methods:

• Crystallography and conductivity measurements of hydrated Gly-Ser.
• Analysis of proton conduction behavior at varying hydration levels (n=0.3, 0.5).
• Investigation of tetrameric Gly-Ser sequences (GSGS, GS50) for proton conduction.

Main Results:

• Proton conductivity in hydrated Gly-Ser crystals arises from hydrogen bond rearrangement within hydration shells.
• A staircase-like change in proton conduction was observed at specific hydration levels.
• Hydration of Gly-Ser tetramers (GSGS, GS50) enables proton conduction, with GS50 showing a diffusion constant of 3.21 × 10⁻⁸ cm²/s.
• Proton conductivity at n=0.3 is attributed to percolation via conductive pathways.

Conclusions:

• Proton transport in Gly-Ser is fundamentally mediated by hydration water.
• The formation of proton-conducting pathways through percolation is key at certain hydration levels.
• Peptide sequences like GSGS and GS50, when hydrated, demonstrate potential for proton conduction applications.