A beaker without walls: formation of deeply supercooled binary liquid solutions of alcohols from nanoscale amorphous solid films

Layered nanoscale amorphous solid films of methanol and ethanol undergo complete intermixing prior to the onset of measurable desorption at 120 K. This intermixing precedes and inhibits crystallization. Subsequent desorption of the film is described quantitatively by a kinetic model describing evaporation from a continuously mixed ideal binary liquid solution. This occurs at temperatures below the melting point of the binary mixture, indicating ideal behavior for the supercooled liquid solution. This approach provides a new method for preparing and examining deeply supercooled solutions.     

Distributed automated docking of flexible ligands to proteins: Parallel applications of AutoDock 2.4

Summary AutoDock 2.4 predicts the bound conformations of a small, flexible ligand to a nonflexible macromolecular target of known structure. The technique combines simulated annealing for conformation searching with a rapid grid-based method of energy evaluation based on the AMBER force field. AutoDock has been optimized in performance without sacrificing accuracy; it incorporates many enhancements and additions, including an intuitive interface. We have developed a set of tools for launching and analyzing many independent docking jobs in parallel on a heterogeneous network of UNIX-based workstations. This paper describes the current release, and the results of a suite of diverse test systems. We also present the results of a systematic investigation into the effects of varying simulated-annealing parameters on molecular docking. We show that even for ligands with a large number of degrees of freedom, root-mean-square deviations of less than 1 Å from the crystallographic conformation are obtained for the lowest-energy dockings, although fewer dockings find the crystallographic conformation when there are more degrees of freedom.The AutoDock 2.4 suite is written in ANSI C, and is supplied with Makefiles for the following platforms: Convex, DEC Alpha OSF/1, Hewlett-Packard Precision Architecture, Silicon Graphics, and Sun. The AutoDock suite of programs is freely available to the noncommercial scientific community and to educational establishments. Further information, including additional figures and MPEG animations showing all docked conformations for each test system, can be found at the following URL: http://www.scripps.edu/pub/olson-web/doc/autodock.     

485—Spectroelectrochemical evidence for imine-alcohol intermediate formed upon electrochemical oxidation of uric acid

Electrochemical oxidation of uric acid in phosphate-containing supporting electrolytes between pH 3–9 at a reticulated vitreous carbon electrode in a thin-layer spectroelectrochemical cell leads to formation of U.V.-absorbing intermediate species. Electrochemical reduction of the intermediate-containing solution leads to the partial regeneration of uric acid. This behavior provides compelling evidence that an imine-alcohol is one of the U.V.-absorbing intermediate species since only this compound may be expected to be reduced to a species which can regenerate uric acid.