Synthesis of neutral and charged porphyrins that selectively bind phosphatidylglycerol, a phospholid found in bacterial membranes
Picket fence porphyrins that bind specifically to phosphatidylglycerol, a bacterial membrane lipid, have been postulated as a receptor component to a synthetic antibiotic. This study reports the synthesis of neutral and charged porphyrins designed with structurally rigid binding pockets that recognize the anionic portion and the bis-hydroxyl portion of the phosphatidylglycerol (PG) anion. Structural characterizations, binding studies, and associated thermodynamics were determined using 1H NMR and ITC (isothermal titration calorimetry) experiments. Fluorescence correlation spectroscopy (FCS) experiments were performed to determine the selectivity and binding constants of receptor 13 in solution and synthetic vesicles containing various compositions of PG and phosphatidylserine (PS) with phosphatidylethanolamine (PE).