Thiol dioxygenases: from structures to functions.

Thiol oxidation to dioxygenated sulfinic acid is catalyzed by an enzyme family characterized by a cupin fold. These proteins act on free thiol-containing molecules to generate central metabolism precursors and signaling compounds in bacteria, fungi, and animal cells. In plants and animals, they also oxidize exposed N-cysteinyl residues, directing proteins to proteolysis. Enzyme kinetics, X-ray crystallography, and spectroscopy studies prompted the formulation and testing of hypotheses about the mechanism of action and the different substrate specificity of these enzymes. Concomitantly, the physiological role of thiol dioxygenation in prokaryotes and eukaryotes has been studied through genetic and physiological approaches. Further structural characterization is necessary to enable precise and safe manipulation of thiol dioxygenases (TDOs) for therapeutic, industrial, and agricultural applications.

Stochastic probability modeling to predict the environmental stability of nanoparticles in aqueous suspension.

The term "nanomaterial" describes a preparation in which the particle size is on the order of 10 to 100 nm in diameter. Such particles have the ability to form suspensions in fluid media such as air and water that can dramatically increase the environmental transport potential in comparision with like materials of larger particle sizes. Quantifying such transport requires an ability to predict the stability of such suspensions as to their tendency to aggregate or interact with other environmental constituents. In this paper, we present a method for predicting the magnitude and uncertainty associated with nanoparticle suspension stability. The critical buoyancy properties are predicted using the Boltzmann equation. The rates of aggregation are then predicted on the basis of molecular collision and adhesion coefficients. The progress of particle growth is simulated across all potential pathways probabalistically using the Gillespie model to characterize the uncertainty. Discussion is provided regarding potential environmental applications and further potential development in predicting particle behavior and effects on the environment.