Previous reports have indicated that parasite actins are short and inherently unstable, despite being required for motility. Here we re-examine the polymerization properties of actin in Toxoplasma gondii, unexpectedly finding that it exhibits isodesmic polymerization in contrast to the conventional nucleation-elongation process of all previously studied actins from both eukaryotes and bacteria....

Double-imaging photoelectron photoion coincidence spectroscopy (i2PEPICO) with tunable synchrotron vacuum ultraviolet radiation was used to record threshold ionization mass spectra of the halocyclohexanes C6H11X (X = Cl, Br, and I). Calculations show that experimental dissociative thresholds correspond thermochemical limits. Among processes observed loss, followed by C2H4 or C3H6 loss; C2H3Cl H...

New energetic ionic liquids are investigated as potential high energy density materials. Ionic liquids are composed of large, charge-diffuse cations, coupled with various (usually oxygen containing) anions. In this work, calculations have been performed on the tetrazolium cation with a variety of substituents. Density functional theory (DFT) with the B3LYP functional, using the 6-311G(d,p) basi...

FtsZ is a bacterial homolog of tubulin that is essential for prokaryotic cytokinesis. In vitro, GTP induces FtsZ to assemble into straight, 5-nm-wide polymers. Here we show that the polymerization of these FtsZ filaments most closely resembles noncooperative (or "isodesmic") assembly; the polymers are single-stranded and assemble with no evidence of a nucleation phase and without a critical con...

The reaction mechanisms by which antioxidants can exert their activity are: hydrogen atom transfer (HAT), proton coupled electron transfer (PCET), sequential proton loss electron transfer (SPLET), single electron transfer proton transfer (SET-PT), radical adduct formation, and sequential proton loss hydrogen atom transfer. The antioxidative activity of different compounds (flavones, flavonols, ...

The mechanism and thermodynamic functions of the self-assembly of a family of covalently linked oligomeric naphthalenediimides (NDIs) were investigated through variable-temperature NMR and CD studies. The NDIs were shown to self-assemble into helical supramolecular nanotubes via an isodesmic polymerisation mechanism, and regardless of the oligomer length a surprising entropy-enthalpy compensati...

Serious (up to 87 kJ mol(-1)) systematic DFT errors in a series of isodesmic reactions are found to be due to the DFT exchange component, and can be largely corrected by substitution of the DFT exchange energy with the Fock exchange energy.

The strain energy in four three-membered rings is calculated by using the appropriate isodesmic reactions. Calculations with and without d functions on the heavy atoms indicate that while these polarization functions tend to reduce ring strain, the addition of d orbitals has little effect on the predicted trends. While introduciton of unsaturation drastically increases the strain in the carbon ...

Generation of vinyl cations is facile by fragmentation of alkenyl(aryl)iodonium trifluoromethanesulfonates. Kinetics and electronic effects were probed by (1)H NMR spectroscopy in CDCl(3). Products of fragmentation include six enol triflate isomers in addition to iodoarenes. The enol triflates arise from direct reaction of a triflate anion with the starting iodonium salts as well as triflate re...