George Gokel
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
"Transport of chloride ion through phospholipid bilayers mediated by synthetic ionophores" G. W. Gokel and N. Barkey, New J. Chem. 2009, 33, 947.
"'Aplosspan': a bilayer-length, ion-selective ionophore that functions in phospholipid bilayers" W. Wang, R. Li and G. W. Gokel, Chem. Commun. 2009, 911.
"A synthetic ion channel derived from a metallogallarene capsule that functions in phospholipid bilayers" O. V. Kulikov, R. Li and G. W. Gokel, Angew. Chem, Int. Ed. 2009, 48, 375.
"Anion transport properties of amine and amide-sidechained peptides are affected by charge and phospholipid composition". L. You, R. Li and G. W. Gokel, Org. & Biomol. Chem. 2008, 6, 2914
"Aggregation behavior and dynamics of synthetic amphiphiles that self-assemble to anion transporters" E. K. Elliott, M. M. Daschbach and G. W. Gokel, Chem.-A Eur. J. 2008, 14, 5871.
"Fluorescent, synthetic amphiphilic heptapeptide anion transporters: evidence for self-assembly and membrane localization in liposomes" L. You and G. W. Gokel, Chem.-A Eur. J. 2008, 14, 5861
"Air-water interfacial behavior of amphiphilic peptide analogs of synthetic chloride ion transporters" E. K. Elliott, K. J. Stine and G. W. Gokel, J. Membrane Sci. 2008, 321, 43.
"Synthetic cation transporters incorporating crown ethers and calixarenes as headgroups and central relays: a comparison of sodium and chloride selectivity" I-S. J. Carlos,W. Wang, R. Ferdani, P. Prados, J. de Mendoza and G. W. Gokel, New J. Chem. 2008, 32, 878.
"Carboxylate anion diminishes chloride transport through a synthetic, self-assembled transmembrane pore" L. You, R. Ferdani, R. Li, J. P. Kramer and R. E. K. Winter and G. W. Gokel, Chem.-A Eur. J. 2008, 14, 382
" The Solid-state Structure of a 4,13-Diaza-18-crown-6 NaI Complex: A Unique Chain-link Assembly". E. S. Meadows, B. D. Levin, E. K. Elliott, L. J. Barbour and G. W. Gokel, J. Chem. Crystallogr. 2008, 38, 425
"Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels" G. W. Gokel and M. M. Daschbach, Coord. Chem. Rev. 2008, 252, 88
"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, J. Phys. Chem. 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 J. Chem.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.