The HCO Potential Energy Surface;

The results from three recent types of experiment investigating the interaction potential between a hydrogen atom and a carbon monoxide molecule are summarized and compared to theoretical predictions based on an ab initio HCO potential energy surface. In the first experiment, energetic hydrogen atoms generated in the photolysis of H 2 S collisionally excite CO molecules to high rotational levels of v = 0, 1, and 2. The product state distributions are compared with the predictions of classical trajectory calculations. In the second experiment, HCO is excited to an upper RennerTeller component that is degenerate with the ground potential energy surface in the linear configuration. Coupling between the states leads to dissociation, and the CO product distribution is again measured and compared to the predictions of classical trajectory calculations. In the third experiment, HCO is prepared by stimulated emission pumping (SEP) in highly excited vibrational levels above the dissociation limit on the ground state potential energy surface. The SEP linewidths provide information about the rate of dissociation, and a measurement of the CO product distribution provides information about the dynamics. Both experimental observations are compared to results from recent wave packet calculations

Time-Resolved Fluorescence-Based Assay for the Determination of Alkaline Phosphatase Activity and Application to the Screening of Its Inhibitors

A single-step end point method is presented for determination of the activity of the enzyme alkaline phosphatase (ALP) using the effect of enhancement of fluorescence of the easily accessible europium(III)-tetracycline 3:1 complex (Eu3TC). Its luminescence, peaking at 616 nm if excited at 405 nm, is enhanced by a factor of 2.5 in the presence of phosphate. Phenyl phosphate was used as a substrate that is enzymatically hydrolyzed to form phenol and phosphate. The latter coordinates to Eu3TC and enhances its luminescence intensity as a result of the displacement of water from the inner coordination sphere of the central metal. The assay is performed in a time-resolved (gated) mode, which is shown to yield larger signal changes than steady-state measurement of fluorescence. The limit of detection for ALP is 4 µmol L—1. Based on this scheme, a model assay for theophylline as inhibitor for ALP was developed with a linear range from 14 to 68 µmol L— 1 of theophylline

Combining proteomics and lipid analysis to unravel Confidor stress response in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae is a useful model for studying the influence of different stress factors on eukaryotic cells. In this work we used the pesticide imidacloprid, in the Confidor® formulation, as the stress factor and analyzed its influence on the metabolic activity, proteome and lipid content and composition of Saccharomyces cerevisiae yeast. During the cultivation of yeast, the lowest recommended application dose of Confidor® (0.025 %, v/v) was added to the growth media and its influence on the mitochondria, cytosol with microsomes and the whole yeast cells was monitored. The results show that under the stress provoked by the toxic effects of Confidor®, yeast cells density significantly decreased and the percentage of metabolically disturbed cells significantly increased comparing with untreated control. Also, there was a downregulation of majority of glycolytic, gluconeogenesis and TCA cycle enzymes (Fba1, Adh1, Hxk2, Tal1, Tdh1, Tdh3, Eno1) thus providing enough acetyl-CoA for the lipid restructuring and accumulation mechanism since we have found the changes in the cell and mitochondrial lipid content and FA composition. This data suggest that lipids could be the molecules that orchestrate the answer of the cells in the stress response to the Confidor® treatment