Kinetic and transport analysis of immobilized oxidoreductases that oxidize glycerol and its oxidation products

Glycerol has drawn increasing attention as a possible fuel, because it has many desirable qualities and is abundant due to the fact that it is a byproduct of biodiesel production. Previous research has shown that non-natural enzyme cascades can be used to create a bioanode that can stepwise oxidize glycerol to carbon dioxide. Two of these enzymes are pyrroloquinoline quinone (PQQ) dependant alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AldDH) derived from Gluconobacter. The third enzyme, which is responsible for carbon bond cleavage, is oxalate oxidase (OxOx) derived from barley. Previous research has shown that all three enzymes have demonstrated the ability to undergo direct electron transfer to a carbon electrode which allows for a simple and efficient bioanode that completely oxidizes glycerol. In this study, each enzyme was individually immobilized within modified Nafion^® on a glassy carbon rotating disc electrode (GC-RDE) and voltammetric analysis was performed employing different rotation rates in a solution containing each enzyme's respective substrate. This substrate was glycerol for alcohol dehydrogenase, glyceraldehyde for aldehyde dehydrogenase, and mesoxalic acid for oxalate oxidase. From the voltammograms, Levich plots were produced and the solution diffusion coefficient (D_soln), the membrane diffusion coefficient (D_film), k_CAT, K_M, and V_MAX were determined.     

Purification of an Inducible DNase from a Thermophilic Fungus

The ability to induce an extracellular DNase from a novel thermophilic fungus was studied and the DNAse purified using both traditional and innovative purification techniques. The isolate produced sterile hyphae under all attempted growing conditions, with an average diameter of 2 μm and was found to have an optimal temperature of 45 °C and a maximum of 65 °C. Sequencing of the internal transcribed region resulted in a 91% match with Chaetomium sp., suggesting a new species, but further clarification on this point is needed. The optimal temperature for DNase production was found to be 55 °C and was induced by the presence of DNA and/or deoxyribose. Static growth of the organism resulted in significantly higher DNase production than agitated growth. The DNase was purified 145-fold using a novel affinity membrane purification system with 25% of the initial enzyme activity remaining. Electrophoresis of the purified enzyme resulted in a single protein band, indicating DNase homogeneity.     

Marketing Netcoatings for Aquaculture

Unsustainable harvesting of natural fish stocks is driving an ever growing marine aquaculture industry. Part of the aquaculture support industry is net suppliers who provide producers with nets used in confining fish while they are grown to market size. Biofouling must be addressed in marine environments to ensure maximum product growth by maintaining water flow and waste removal through the nets. Biofouling is managed with copper and organic biocide based net coatings. The aquaculture industry provides a case study for business issues related to entry of improved fouling management technology into the marketplace. Several major hurdles hinder entry of improved novel technologies into the market. The first hurdle is due to the structure of business relationships. Net suppliers can actually cut their business profits dramatically by introducing improved technologies. A second major hurdle is financial costs of registration and demonstration of efficacy and quality product with a new technology. Costs of registration are prohibitive if only the net coatings market is involved. Demonstration of quality product requires collaboration and a team approach between formulators, net suppliers and farmers. An alternative solution is a vertically integrated business model in which the support business and product production business are part of the same company.     

ELASTIC AND VISCOUS PROPERTIES OF SEVERAL POTASH-SILICA GLASSES IN THE ANNEALING RANGE OF TEMPERATURE*

Quantitative data are presented, and conclusions are drawn regarding the molecular nature of elastic and viscous processes in certain silicate glasses.     

Adaptive Fourier Series and the Analysis of Periodicities in Time Series Data

A Fourier series decomposes a function x ( t ) into a sum of periodic components that have sinusoidal shapes. This paper describes an adaptive Fourier series where the periodic components of x ( t ) may have a variety of differing shapes. The periodic shapes are adaptive since they depend on the function x ( t ) and the period. The results, which extend both Fourier analysis and Walsh–Fourier analysis, are applied to investigate the shapes of periodic components in time series data sets.     

Mono-, Bi- and Multifunctional Single-Sites: Exploring the Interface Between Heterogeneous and Homogeneous Catalysis

This mini-review contrasts the characteristics of traditional heterogeneous (solid) catalysts with those of homogeneous ones: the nature of the active sites in each case is very different, a fact well illustrated in ammonia synthesis. It is recalled that certain chemical transformations can be effected only with heterogeneous catalysts. It is also demonstrated that the scope for introducing multifunctional sites is greater with open-structured inorganic heterogeneous catalysts than with homogeneous ones: for example, Ti^IV ions distributed in a spatially isolated and accessible manner at the large areas of a nanoporous support smoothly convert cyclohexene to adipic acid (with H₂O₂) in a cascade of six consecutive reactions. A sharp distinction is drawn between nanocluster and nanoparticle “metal” catalysts, both electronic and geometric arguments being utilized to explain this difference. In the extreme case, a few (or single) metal atoms (supported on oxides) have been shown (see refs. Fu et al. Science 301:935, 2003 and Rim et al J Phys Chem C 113:10198, 2009) to be more important determinants of catalytic activity than nanoparticle metals such as Au and Pd. Recent advances in high-resolution electron microscopy is a key technique in this facet of catalysis. The merits of immobilizing single-site homogeneous catalysts and of creating atomically well-defined single-site heterogeneous ones on high-area solids are illustrated both from a practical viewpoint and also as a strategy for the design of new catalysts.     

The coating chemist as expert witness

Conclusion  The consulting chemist can find entertaining and remunerative employment as an expert for the law in preparation for the courtroom. The problems presented are interesting and the expert learns a lot from the wide variety of details involved in a case, as well as performing a useful service to the court, the community, and the client. Presented at the 24th Biennial Western Coatings Societies Symposium, in Sparks, NV, on February 15–17, 1999. P.O. Drawer 7, El Cerrito, CA 94530-0007.