APL@Voro: a Voronoi-based membrane analysis tool for GROMACS trajectories.

APL@Voro is a new program developed to aid in the analysis of GROMACS trajectories of lipid bilayer simulations. It can read a GROMACS trajectory file, a PDB coordinate file, and a GROMACS index file to create a two-dimensional geometric representation of a bilayer. Voronoi diagrams and Delaunay triangulations--generated for different selection models of lipids--support the analysis of the bilayer.

Dimerization is required for the activity of the protein histidine kinase CheA that mediates signal transduction in bacterial chemotaxis.

The histidine protein kinase CheA plays an essential role in stimulus-response coupling during bacterial chemotaxis. The kinase is a homodimer that catalyzes the reversible transfer of a gamma-phosphoryl group from ATP to the N-3 position of one of its own histidine residues. Kinetic studies of rates of autophosphorylation show a second order dependence on CheA concentrations at submicromolar levels that is consistent with dissociation of the homodimer into inactive monomers.

Magnetic resonance spectroscopy, calcium content, and anion coordination studies of bovine and goat lactoperoxidase.

Bovine lactoperoxidase from two purebred strains and a commercial source as well as lactoperoxidase isolated from Alpine goat milk were examined by proton NMR spectroscopy for structural comparison of the heme site. Hyperfine shifted proton NMR spectra for both the native enzymes and cyanide complexes were equivalent for the protein obtained from the four separate sources. Activity assays (guaiacol and iodide ion oxidations) were also employed to compare the enzyme from various sources.

Response regulation in bacterial chemotaxis.

The signal transduction system that mediates bacterial chemotaxis allows cells to modulate their swimming behavior in response to fluctuations in chemical stimuli. Receptors at the cell surface receive information from the surroundings. Signals are then passed from the receptors to cytoplasmic chemotaxis components: CheA, CheW, CheZ, CheR, and CheB.