title: Stochastic sensing of TNT with a genetically engineered pore.
abstract: Engineered versions of the transmembrane protein pore alpha-hemolysin (alphaHL) can be used as stochastic sensing elements for the identification and quantification of a wide variety of analytes at the single-molecule level. Until now, nitroaromatic analytes have eluded detection by this approach. We now report that binding sites for nitroaromatics can be built within the lumen of the alphaHL pore from simple rings of seven aromatic amino acid side chains (Phe, Tyr or Trp). By monitoring the ionic current that passes through a single pore at a fixed applied potential, various nitroaromatics can be distinguished from TNT on the basis of the amplitude and duration of individual current-blocking events. Rings of less than seven aromatics bind the analytes more weakly; this suggests that direct aromatic-aromatic interactions are involved. The engineered pores should be useful for the detection of explosives and, in combination with computational approaches and structural analysis, they could further our understanding of noncovalent interactions between aromatic molecules.
authors.affiliation: Department of Medical Biochemistry & Genetics, The Texas A&M University System Health Science Center, College Station, Texas 77843-1114, USA.
authors.forename: Xiyun
authors.initials: X
authors.lastname: Guan
authors.forename: Li-Qun
authors.initials: LQ
authors.lastname: Gu
authors.forename: Stephen
authors.initials: S
authors.lastname: Cheley
authors.forename: Orit
authors.initials: O
authors.lastname: Braha
authors.forename: Hagan
authors.initials: H
authors.lastname: Bayley
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008564:Membrane Potentials; D008958:Models, Molecular; D016254:Mutagenesis, Insertional; D015202:Protein Engineering; D014303:Trinitrotoluene / Q000032:analysis* / Q000737:chemistry
chemical_list: D006460:Hemolysin Proteins; D014303:Trinitrotoluene