Redox and electrophilic properties of vapor- and particle-phase components of ambient aerosols.

Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semi-volatile components may also contribute to many adverse health effects.

Electrophilic and redox properties of diesel exhaust particles.

The adverse health effects of air pollutants have been associated with their redox and electrophilic properties. Although the specific chemical species involved in these effects are not known, the characterization of their general physical and chemical properties is important to our understanding of the mechanisms by which they cause health problems. This manuscript describes results of a study examining the partition properties of these activities in aqueous and organic media.

Antioxidant actions of nitroxyl (HNO).

Nitrogen oxides are endogenously produced signaling/effector molecules that have the potential to both cause and ameliorate oxidative stress. Whether nitrogen oxides behave as oxidants or antioxidants is dependent on many factors including the cellular environment, the concentration, and the presence of other reactive species. To date, the nitrogen oxide nitroxyl (HNO) has only been reported to possess prooxidant properties.

Yeast model systems for examining nitrogen oxide biochemistry/signaling.

The yeast Saccharomyces cerevisiae is an ideal model system for examining fundamental nitrogen oxide biochemistry. The utility of this model system lies in both the similarities and the differences between yeast and mammalian cells. The similarities between the two systems, with regards to many of the fundamental biochemical processes, allow studies in yeast to be extrapolated to mammalian systems.

Inhibition of yeast glycolysis by nitroxyl (HNO): mechanism of HNO toxicity and implications to HNO biology.

Nitroxyl (HNO) was found to inhibit glycolysis in the yeast Saccharomyces cerevisiae. The toxicity of HNO in yeast positively correlated with the dependence of yeast on glycolysis for cellular energy. HNO was found to potently inhibit the crucial glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH), an effect which is likely to be responsible for the observed inhibition of glycolysis in whole cell preparations.

An examination of quinone toxicity using the yeast Saccharomyces cerevisiae model system.

The toxicity of quinones is generally thought to occur by two mechanisms: the formation of covalent bonds with biological molecules by Michael addition chemistry and the catalytic reduction of oxygen to superoxide and other reactive oxygen species (ROS) (redox cycling). In an effort to distinguish between these general mechanisms of toxicity, we have examined the toxicity of five quinones to yeast cells as measured by their ability to reduce growth rate. Yeast cells can grow in the presence and absence of oxygen and this feature was used to evaluate the role of redox cycling in the toxicity of each quinone.

Inhibition of the yeast metal reductase heme protein fre1 by nitric oxide (NO): a model for inhibition of NADPH oxidase by NO.

Nitric oxide (NO) has been found to inhibit the actions of the transmembrane metal reductase Fre1 in the yeast Saccharomyces cerevisiae. This membrane-spanning heme protein is homologous to the gp91(PHOX) protein of the NADPH oxidase enzyme complex and is responsible for reducing extracellular oxidized metals (i.e.

Nitroxyl-mediated disruption of thiol proteins: inhibition of the yeast transcription factor Ace1.

Among the biologically and pharmacologically relevant nitrogen oxides, nitroxyl (HNO) remains one of the most poorly studied and least understood. Several previous reports indicate that thiols may be a primary target for the biological actions of HNO. However, the intimate details of the chemical interaction of HNO with biological thiols remain unestablished.