George Gokel

barton1 Professor Gokel attended Tulane University, New Orleans, LA, B.S. chemistry, 1968, University of Southern California, Los Angeles, CA, Ph.D. chemistry with I. K. Ugi, 1971 and UCLA, where he did a postdoctoral fellowship with D.J. Cram, 1972-1974. He served on the faculty at Penn State, Maryland and Miami prior to heading the Program in Chemical Biology, Washington University School of Medicine, St. Louis. He joined UM-St. Louis as Distinguished Professor in 2006.

gokelg@umsl.edu
Office: B428
Phone: (314) 516-5321
Fax: (314) 516-5342

Professor Gokel's Research Home Page

Research Interests

Cation-π interactions
Cation-pi interactions occur between positive ions and electron-rich species such as double bonds, triple bonds, and arenes. The pi-electron system may be neutral or anionic, but the latter are generally less relevant to biology, at least so far as is currentlyknown. Among the 20 common amino acids, there are four aromatic residues. These are benzene, phenol, indole, and imidazole, on the side chains of phenylalanine, tyrosine, tryptophan, and histidine, respectively. Of these, imidazole is expected to be a σ-donor, and benzene, phenol, and indole are anticipated to serve as π-donors. Sodium and potassium are the most abundant metal cations in living systems. We have developed an experimental system to probe, especially by X-ray crystallography, the interactions that occur between Na⁺ or K⁺ and the neutral arenes of particular biological significance.

Synthetic Cation and Anion channels
During the past decade, our lab has developed and elaborated a class of synthetic ion channels called hydraphiles . We use diaza-18-crown-6 macrocycles as head groups and entry portals for ion conduction. Hydrophobic spacer chains connect the headgroups and impart the appropriate length for the hydraphile to span the bilayer. A third, central macrocycle was incorporated to act as an ion relay. This subunit serves the same purpose as the recently discovered "water and ion-filled capsule" identified in the solid state structure of KcsA channel of Streptomyces lividans. A side arm of varying identity extends from the distal crown, providing anchoring and stabilization in the bilayer.

Synthetic Anion Transporters:
Anion, particularly chloride, permeability is essential for volume, pH, and membrane potential regulation in all cells. We have developed a chloride-selective channel in an attempt to model anion transport and explore these cellular requirements. Using known protein chloride channels as a guide, we have synthesized a chloride-selective transporter that is active in phospholipid bilayers.

Selected Recent Publications

"Heterocyclic amide hydraphile synthetic cation transporters". W. Wang, C. R.Yamnitz and G. W. Gokel, Heterocycles, 2007, 73, 825.

"K-39 Quadrupolar and Chemical Shift Tensors for Organic Potassium Complexes and Diatomic Molecules". P. K. Lee, R. P.;Chapman, L. Zhang, J. Hu, L. J. Barbour, E. K. Elliott, G. W. Gokel and D. L. Bryce, Journal of Physical Chemistry A, 2007, 111, 12859.

"The effect of midpolar regime mimics on anion transport mediated by amphiphilic heptapeptides". R. Pajewski, J. Pajewska, R. Li, M. M. Daschbach, E. A.; Fowler and G. W.Gokel, New Journal of Chemistry, 2007, 31, 1960.

"Transport of chloride and carboxyfluorescein through phospholipid vesicle membranes by heptapeptide amphiphiles". R. Ferdani, R. Li, R. Pajewski, J. Pajewska, R. E. K. Winter and G. W. Gokel, Org. Biomolec. Chem., 2007, 5, 2423.

"Synthetic, biologically active amphiphilic peptides". C. R. Yamnitz and G. W. Gokel, Chem. Biodiversity, 2007, 4, 1395.

"The Fluorescence Properties of Free and Cation-complexed Lariat Ethers having Sidearms Terminated by a Benzene Ring". E. K. Elliott, J. Hu and G. W. Gokel, Supramolecular Chem. 2007, 19, 175.

"Biologically active, synthetic ion transporters". G. W. Gokel and I. A. Carasel, Chem. Soc. Rev. 2007, 36, 378.

"Synthetic ion channels as novel antimicrobial agents". Z. T. Cusumano, G. W.Gokel, Current Bioactive Compounds, 2006, 2, 13.

"Solid-State ²³Na NMR Study of Sodium Lariat Ether Receptors Exhibiting Cation-p Interactions". D. L. Bryce, S. Adiga, E. K. Elliott and G. W. Gokel, J. Phys. Chem. 2006, 110A, 13568.

"Planar bilayer studies reveal multiple conductance states for synthetic anion transporters". R. L. Ferdani and G. W. Gokel. Org. Biomolec. Chem. 2006, 4, 3746.

"Mixed Monolayers of Alkylated Azacrown Ethers and Palmitic Acid at the Air-Water Surface". K. Wojciechowski, D. Grigoriev, R. Ferdani and G. W. Gokel, Langmuir, 2006, 22, 8409.

"The influence of varied amide bond positions on hydraphile ion channel activity". M. E. Weber, W. Wang, S. E. Steinhardt, M. R. Gokel, M. L. Leevy and G. W. Gokel, New J. Chem. 2006, 30, 177.

"Chloride ion efflux from liposomes is controlled by sidechains in a channel-forming heptapeptide". L. You, R. Ferdani and G. W. Gokel, Chem. Commun. 2006, 603.

"NMR Structure and Dynamic Studies of an Anion-Binding, Channel-Forming Heptapeptide". G. A. Cook, R. Pajewski, M. Aburi, P. E. Smith, O. Prakash, J. M. Tomich and G. W. Gokel, J. Am. Chem. Soc. 2006, 128, 1633.

"A synthetic, chloride-selective channel that alters chloride transport in epithelial cells". R. Pajewski, R. Garcia-Medina, S. L. Brody, M. L. Leevy, P. H. Schlesinger and G. W. Gokel, Chem. Commun. 2006, 329