Improvement of Thermal Stability of Amphipathic Peptide-Phospholipid Nanodiscs via Lateral Association of a-Helices by Disulfide Cross-Linking

(doi: 10.1021/acs.langmuir.2c00533)

Laura Martin

Cal Poly Humboldt Biochemistry Major

November 18th, 2022 2:00 – 2:50PM (SciA 564)

ABSTRACT

Delivering hydrophobic and amphipathic pharmaceuticals orally or intravenously into aqueous environments is challenging due to their low solubility. The mechanisms for studying membrane proteins, which have hydrophilic and hydrophobic segments, have been proposed as carriers for drug delivery due to their similar properties, allowing for the pharmaceutical's encapsulation and transport in the aqueous environment. Many different structures have been developed and tested to stabilize and homogenize extracted membrane proteins, but not all of them have proven to be effective in drug administration. Nanodiscs are a recent development in membrane protein study that also offers a safer and more effective method of drug delivery. Nanodiscs were modeled after the human body's natural process of transporting cholesterol around the body via high-density lipoproteins (HDLs). They consist of a lipid bilayer encircled by a scaffold protein holding the structure together, and can carry a membrane protein or a drug for cellular delivery or further studies. The protein Apolipoprotein A-I (ApoAI) is a derivative of HDLs that has been used as a scaffold protein in nanodiscs, but comes at a high cost of time and resources to obtain or synthesize. Peptide-based nanodiscs offer a cheaper alternative to membrane scaffold protein (MSP) nanodiscs, but they degrade at temperatures >40℃. One such peptide used in this study, peptide 37pA-C2, was developed as a mutant of peptide 37pA where alanine residues at positions 11 and 30 are replaced with cystines. The application of this peptide in nanodiscs was shown to greatly increase thermal stability via disulfide cross-linkages, making them more stable in drug applications.