Effect of the electrostatic potential on the internalization mechanism of cell penetrating peptides derived from TIRAP

Selectivity of membrane-active peptides: the role of electrostatics and other membrane biophysical properties

Membrane-active peptides (MAPs) are versatile molecules that interact with lipid bilayers, facilitating processes such as antimicrobial defense, anticancer activity, and membrane translocation. Given that most MAPs are cationic, their selectivity for specific cell membranes has traditionally been attributed to variations in membrane surface charge. However, growing evidence suggests that electrostatics alone cannot fully explain MAPs selectivity. Instead, MAPs activity is also strongly influenced by other membrane biophysical properties, such as lipid packing, phase state, curvature, and the spatial distribution of hydrophobic and charged residues within the peptide sequence. In this review, we summarize the current knowledge on the biophysical determinants of MAPs selectivity. We begin by examining membrane and cell surface electrostatics and their influence on MAPs-membrane interactions, including electrostatically driven peptide conformational changes and lipid recruitment. We then broaden the discussion to include non-electrostatic factors, such as membrane curvature and rheology, which are primarily influenced by sterol or hopanoid content, as well as acyl chain unsaturation and branching. Together, these processes highlight that MAPs selectivity is not governed by any single membrane property but instead emerges from a synergistic interplay of electrostatic, hydrophobic, and topological factors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12551-025-01309-7.

Sodium carboxymethyl celluloses as a cryoprotectant for survival improvement of lactic acid bacterial strains subjected to freeze-drying

This study investigated the possibility of sodium carboxymethyl celluloses (Na-CMC) in protecting the viability of lactic acid bacteria (LAB) against freeze-drying stress. 1 % concentration of Na-CMC with a 0.7 substitution degree and viscosity of 1500 to 3100 (MPa.s) was found to protect Lactobacillus delbrueckii subsp. bulgaricus CICC 6098 best, giving a high survival rate of 23.19 ± 0.88 %, high key enzymatic activities, and 28-day storage stability. Additionally, Na-CMC as cryoprotectant provided good protection for other 7 lactic acid bacterial strains subjected to freeze-drying. The highest survival rate was 48.79 ± 0.20 U/mg for β-GAL, 2.75 ± 0.15 U/mg for Na+-K+-ATPase, and 2.73 ± 0.41 U/mg for Ca2+-Mg2+-ATPase as 48.48 ± 0.46 % for freeze-dried Pediococcus pentosaceus CICC 22228. It was Interesting to note that the presence of Na-CMC reduced the freezable water content of the lyophilized powders containing the tested strains through its hydroxyl group, and supplied micro-holes and fibers for protecting the integrated structure of LAB cell membrane and wall against the freezing damage. It is clear that addition of Na-CMC should be promising as a new cryoprotective agent available for processing the lyophilized stater cultures of LAB strains.

Prediction of Cell-Penetrating Peptides

The in silico methods for the prediction of the cell-penetrating peptides are reviewed. Those include the multivariate statistical methods, machine-learning methods such as the artificial neural networks and support vector machines, and molecular modeling techniques including molecular docking and molecular dynamics.The applicability of the methods is demonstrated on the basis of the exemplary cases from the literature.