Sensing an Opening

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Science  29 Oct 2004:
Vol. 306, Issue 5697, pp. 781
DOI: 10.1126/science.306.5697.781c

One way to monitor enzyme activity is to use synthetic membrane pores. Vesicles containing blocked pores can be loaded with fluorescent dye at high enough concentrations for self-quenching; enzyme activity then removes the blockers, and the efflux of the dye allows fluorescence. One drawback of these approaches is that the enzyme must be able to enter the pores. Gorteau et al. describe an approach in which products of enzyme activity bind to pore precursors to create nascent open pores that permeabilize the pores. A rigid-rod octiphenyl core bearing peptide side chains with a central arginine group forms a β-barrel pore upon binding of acidic ligands with hydrophobic tails. The authors followed the activity of pig liver esterase using pyrenebutyrate methylester as a substrate, which generated pyrene carboxylate as a product to create open pores. The pores are lined internally with His-His groups and can be blocked by the addition of larger molecules such as poly-L-glutamate, probably through the formation of an α-helix. — PDS

J. Am. Chem. Soc. 126, 13592 (2004).

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