Creation of cross-linked bilayer membranes that can incorporate membrane proteins from oligo-Asp-based peptide gemini surfactants

Facile design of gemini surfactant-like peptide for hydrophobic drug delivery and antimicrobial activity

Recently, many kinds of gemini-type amphiphilic peptides have been designed and shown their advantage as self-assembling nanomaterials. In this study, we proposed a simple strategy to design gemini surfactant-like peptides, which are only composed of natural amino acids and can be easily obtained by conventional peptide sythnesis. Taking two prolines as the turn-forming units, a peptide named APK was designed. The petide has a linear sequence but naturally takes the conformation like a gemini surfactant. Compared with a single-tailed surfactant-like peptide A6K, APK showed much stronger ability to undergo self-assembly and to encapsulate hydrophobic pyrene. Several hydrophobic drugs including paclitaxel, doxorubicin, etomidate and propofol were encapsulated by APK, and the corresponding formulations showed anti-tumor or anesthetic efficacy comparable to their respective clinical formulations. Furthermore, APK could inhibit the growth of different microorganisms including E. coli, S. aureus and C. albicans. Etomidate and propofol formulations encapsulated by APK also showed strong antimicrobial activity. Taking APK as an example, our study indicated a straightforward strategy to design gemini surfactant-like peptides, which could be potential nanomaterials for exploring hydrophobic drug formulations with efficacy, safety and self-antimicrobial activity.

Design of New Extraction Surfactants for Membrane Proteins from Peptide Gemini Surfactants

The development of additional extraction surfactants for membrane proteins is necessary for membrane protein research, since optimal combinations for the successful extraction of target membrane proteins from biological membranes that minimize protein denaturation are hard to predict. In particular, those that have a unique basal molecular framework are quite attractive and highly desired in this research field. In this study, we successfully constructed a new extraction surfactant for membrane proteins, NPDGC₁₂KK, from the peptide-gemini-surfactant (PG-surfactant) molecular framework. The PG-surfactant is a U-shaped lipopeptide scaffold, consisting of a short linker peptide (-X-) between two long alkyl-chain-modified Cys residues and a peripheral peptide (Y-) at the N-terminal side of long alkyl-chain-modified Cys residues. Using photosystem I (PSI) and photosystem II (PSII) derived from Thermosynecoccus vulcanus as representative membrane proteins, we evaluated whether NPDGC₁₂KK could solubilize membrane proteins while maintaining structure and functions. Neither the membrane integral domain nor the cytoplasmic domain of PSI and PSII suffered any damage upon the use of NPDGC₁₂KK based on detailed photophysical measurements. Using thylakoid membranes of T. vulcanus as a representative biological membrane sample, we performed experiments to extract membrane proteins, such as PSI and PSII. Based on the extraction efficiency and maintenance of protein supramolecular structure established using clear native-PAGE analyses, we proved that NPDGC₁₂KK functions as a novel class of peptide-containing extraction surfactants for membrane proteins.