Molecular Mechanism of Cell Membrane Protection by Sugars: A Study of Interfacial H-Bond Networks

Sugars function as bioprotectants by stabilizing biomolecules during dehydration, thermal stress, and freeze-thaw cycles. A buildup of sugars occurs in many organisms upon their exposure to extreme conditions. Understanding sugar's bioprotective effects on membranes is achieved by characterizing the H-bond networks at the lipid-water interface. Here, we report the headgroup H-bond populations, structures, and dynamics of 1,2-dimyristoyl-sn-glycero-3-phosphocholine vesicles in concentrated glucose solutions using ultrafast two-dimensional infrared spectroscopy in conjunction with molecular dynamics simulations. H-Bond populations and dynamics at the ester carbonyl positions are largely unaffected even at very high, 600 mg/mL, sugar concentrations. In addition, dynamics exhibit a slight nonmonotonic dependence on sugar concentration. Simulations, which are in near-quantitative agreement with measured dynamics, show that the H-bond structure remains largely intact by the existence of sugar. This study shows that the bioprotection of sugar is realized through stable lipid-saccharide-water H-bond networks at the membrane interface that mimic the H-bond networks in pure water.

Automated summary

This study reveals the mechanism of sugar's bioprotective effects on lipid membranes by maintaining stable hydrogen bond networks at the membrane interface. Sugars help reduce damage to organisms exposed to extreme conditions by stabilizing the lipid surface.