Dataset and kinetic model reaction compilation for the radical-induced degradation of formic acid and formate in aqueous solution.

This article contains the individual datasets and complete reaction kinetics compilation for the formic acid/formate component of the kinetic model described in "Radiolytic Degradation of Formic Acid and Formate in Aqueous Solution: Modeling the Final Stages of Organic Mineralization under Advanced Oxidation Process Conditions" [1]. Gamma irradiation data were collected for aqueous sodium formate solutions under pH = 1.5 and 9.0 conditions. To determine the optimum conditions necessary to effectively mineralize formic acid/formate in an Advanced Oxidation Process utilized for water treatment, several solution compositions were evaluated: air, nitrogen, and nitrous oxide saturation. Data were collected by a combination of high performance liquid chromatography and gas chromatography. These measured values were used to construct a kinetic computer model, by combining with published literature rate coefficients and optimizing specific important rate coefficients to afford the best agreement with experimental data.

Radiolytic degradation of formic acid and formate in aqueous solution: modeling the final stages of organic mineralization under advanced oxidation process conditions.

The successful use of advanced oxidation processes to treat aqueous solutions containing undesirable organic species requires the degradation of these species to lower molecular weight, lower hazard compounds. Safe application of this technology requires a thorough understanding of the mechanisms of degradation. These oxidative transformations are mainly initiated by the reactions of reactive oxygen species, particularly hydroxyl radicals. These react with organic molecules to generate carbon-centered radicals. In the presence of dissolved oxygen, the carbon-centered radicals are next converted to peroxyl radicals, which then decay to lower molecular weight species by multiple mechanistic pathways. Formic acid and its conjugate base formate are the last stable chemical species produced immediately before the complete mineralization of any organic molecule undergoing oxidative degradation in aqueous solution. Once understood, the radical-induced chemistry of formic acid/formate under these conditions has wide applicability in all advanced oxidation technologies. To develop this quantitative knowledge, we have performed a series of 60Co gamma irradiation studies on aqueous formic acid/formate over different pH and solution conditions. The measured species concentration changes, as a function of applied dose, are compared with the predictions of a kinetic computer model constructed from literature reactions and reported rate coefficients. The excellent agreement found between the results and modeling gives confidence in the mechanism presented here and provide the first complete computer model for the radiolytic degradation of formic acid in water.

Design and synthesis of potent Gram-negative specific LpxC inhibitors.

Antibiotic resistant hospital acquired infections are on the rise, creating an urgent need for novel bactericidal drugs. Enzymes involved in lipopolysaccharide (LPS) biosynthesis are attractive antibacterial targets since LPS is the major structural component of the outer membrane of Gram-negative bacteria. Lipid A is an essential hydrophobic anchor of LPS and the first committed step in lipid A biosynthesis is catalyzed by a unique zinc dependent metalloamidase, UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC). LpxC is an attractive Gram-negative only target that has been chemically validated by potent bactericidal hydroxamate inhibitors that work by coordination of the enzyme's catalytic zinc ion. An exploratory chemistry effort focused on expanding the SAR around hydroxamic acid zinc-binding 'warheads' lead to the identification of novel compounds with enzyme potency and antibacterial activity similar to CHIR-090.

Crystallization and preliminary X-ray analysis of the acyl carrier protein synthase (AcpS) from Staphylococcus aureus.

Acyl carrier protein synthase (AcpS) catalyzes the transfer of 4'-phophopantetheine from coenzyme A to the acyl carrier protein (ACP) to activate it for fatty-acid biosynthesis. Two crystal forms of Staphylococcus aureus AcpS have been generated at 277 K using either NaCl or PEG 6000 as a precipitant. The diffraction patterns of the crystals extend to 1.65 and 1.8 A, respectively. Full sets of X-ray diffraction data were collected from native crystals and the crystal structures were solved by molecular replacement.