SYNTHETIC SODIUM TRANSPORTER
Celia Henry Arnaud · Chemical & Engineering News · 2006
RESEARCHERS HAVE TAKEN A step closer to a new type of synthetic ion channel witha G-quadruplex that acts as a sodium transporter ( J. Am. Chem. Soc. 2006, 128,38). Such transporters could eventually serve as sensors or antimicrobial agents. G-quadruplexes are guaninerich structures that bind metal cations. They are usually made of nucleic acids, but such hydrophilic structures aren't stable in the hydrophobic environment of a phospholipid membrane. A team led by Jeffery T. Davis, a professor of chemistry and biochemistry at the University of Maryland, makes guanosine lipophilic by adding side chains to the ribose, but such modifications alone aren't enough. "For three or four years, we've been trying to make ion channels by assembling lipophilic guanosine derivatives into G-quadruplex structures," Davis says. "Although they're stable in organic solvents, they don't seem to have the properties we want in a membrane." Grad student Mark S. Kaucher and Davis achieve the function they want by adding polymerizable groups—allyl ethers—to the ribose. Templated by potassiumions, 16 monomers of the guanosine derivative form a noncovalent assembly of four G-quartet layers of four monomers each. The entire structure is stitched together via ...