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The applications of 1H and 13C nuclear magnetic resonance (NMR) and two-dimensional 1H/13C NMR spectroscopy have been shown to be useful techniques for the qualitative and quantitative characterization of hydrotreated recycled lube oils. The addition of hydrogen to aromatic and alkene hydrocarbons can be quantitatively and selectively measured. The decrease of oxygen/nitrogen/sulfur species can also be inferred from the reduction of specific resonances in the NMR spectra. Treated recycled lube oil was subsequently hydrotreated with Pd catalysts deposited by either atomic layer deposition (ALD) or incipient wetness impregnation (IWI) on a SiO2/Al2O3 support. In both cases, much lower hydrogenation temperatures were required than had been observed with typical NiMo or CoMo on Al2O3. In addition, the ALD-deposited catalyst was more effective for the reduction of aromatics and heteroatom components than the IWI catalyst. The lube oil fractions were of high purity (low aromaticity and low heteroatom content) e...

The replacement of petrochemicals with biobased chemicals requires efficient bioprocesses, biocatalysis, and product recovery. Biocatalysis (e.g., enzyme conversion and fermentation) offers an attractive alternative to chemical processing because biocatalysis utilize renewable feedstocks under benign reaction conditions. One class of chemical products that could be produced in large volumes by biocatalysis is organic acids. However, biocatalytic reactions to produce organic acids typically result in only dilute concentrations of the product because of product inhibition and acidification that drives the reaction pH outside of the optimal range for the biocatalyst. Buffering or neutralization results in formation of the acid salt rather than the acid, which requires further processing to recover the free acid product. To address these barriers to biocatalytic organic acid production, we developed the “separative bioreactor” based on resin wafer electrodeionization, which is an electro-deionization platform that uses resin wafers fabricated from ion exchange resins. The separative bioreactor simultaneously separates the organic acid from the biocatalyst as it is produced, thus it avoids product inhibition enhancing reaction rates. In addition, the separative bioreactor recovers the product in its acid form to avoid neutralization. The instantaneous separation of acid upon formation in the separative bioreactor is one of the first truly one-step systems for producing organic acids. The separative bioreactor was demonstrated with two systems. In the first demonstration, the enzyme glucose fructose oxidoreductase (GFOR) was immobilized in the reactor and later regenerated in situ. GFOR produced gluconic acid (in its acid form) continuously for 7 days with production rates up to 1000 mg/L/hr at >99% product recovery and GFOR reactivity >30mg gluconic acid/mg GFOR/hour. In the second demonstration, the E. coli strain CSM1 produced lactic acid for up to 24 hours with a productivity of >200 mg/L/hr and almost 100% product recovery.

Perfluorosulfonated ionomer membranes (Nafion®) were modified by a chemical treatment to increase the permeability of membrane structures. The treatment consisted of a single phase propylene carbonate–water mixture which, in the presence of the sulfonic acid groups of the Nafion®, yielded CO2. This CO2 presumably expanded having the effect of creating larger pores within the Nafion® framework. The resulting membrane had filtration characteristics in the ultrafiltration–microfiltration range with a maximum flux of ∼10 kg m−2 h at 1.3782 × 105 Pa (20 psig). These structures were characterized using flux, solute rejection, neutron scattering and water volume measurements. Further, these membranes were found to be suitable for emulsion separations with the water phase permeating through the membrane. In preliminary results, a water–xylene mixture exhibited a single phase permeate with approximately 60% of the flux of pure water.

One of the clinical manifestations of Alzheimer's disease is the deposition of the 39–43 residue amyloid-beta (A beta) peptide in aggregated fibrils in senile plaques. Characterization of the aggregation behavior of A beta is one of the critical issues in understanding the role of A beta in the disease process. Using solution hydrodynamics, A beta was observed to form three types of species in phosphate-buffered saline: insoluble aggregates with sedimentation coefficients of approximately 50,000 S and molecular masses of approximately 10(9) Da, "soluble aggregates" with sedimentation coefficients of approximately 30 S and masses of approximately 10(6) Da, and monomer. When starting from monomer, the aggregation kinetics of A beta 1–40 (A beta 40) and A beta 1–42 (A beta 42), alone and in combination, reveal large differences in the tendency of these peptides to aggregate as a function of pH and other solution conditions. At pH 4.1 and 7.0–7.4, aggregation is significantly slower than at pH 5 and 6. Under all conditions, aggregation of the longer A beta 42 was more rapid than A beta 40. Oxidation of Met-35 to the sulfoxide in A beta 40 enhances the aggregation rate over that of the nonoxidized peptide. Aggregation was found to be dependent upon temperature and to be strongly dependent on peptide concentration and ionic strength, indicating that aggregation is driven by a hydrophobic effect. When A beta 40 and A beta 42 are mixed together, A beta 40 retards the aggregation of A beta 42 in a concentration-dependent manner. Shorter fragments have a decreasing ability to interfere with A beta 42 aggregation. Conversely, the rate of aggregation of A beta 40 can be significantly enhanced by seeding slow aggregating solutions with preformed aggregates of A beta 42. Taken together, the inhibition of A beta 42 aggregation by A beta 40, the seeding of A beta 40 aggregation by A beta 42 aggregates, and the chemical oxidation of A beta 40 suggest that the relative abundance and rates of production of different-length A beta and its exposure to radical damage may be factors in the accumulation of A beta in plaques in vivo.

The electron spin polarized (ESP) electron paramagnetic resonance (EPR) signal observed in spinach Photosystem I (PS I) particles was examined in preparations depleted of vitamin K 1 by solvent extraction, followed by reconstitution with a series of quinones and quinone analogues. The ESP EPR signal was previously attributed to a radicalpair that included vitaim K 1 − (Rustandi, R.R., et al. (1990) Biochemistry 29, 8030–8032) and, in addition, vitamin K 1 was assigned as the secondary acceptor A 1 in PS I (Snyder, S.W., et al. (1991) Proc. Natl. Acad. Sci. USA, 88, 9895–9896). The ESP EPR signal was observed in untreated PS I preparations, was not detected in the solvent-extracted PS I samples and was restored upon reconstitution using certain quinones. The ability to restore the ESP EPR signal was dependent upon two properties of the reconstituted acceptor. First, the solution reduction potential of the reconstituted acceptor must be more positive than about −750 mV where the solution reduction potential of vitamin K 1 is −710 mV. Second, the structure of the reconstituted acceptor requires either a minimum of two aromatic rings (i.e., naphthoquinone) or a benzoquinone (or larger) derivative substituted with an alkyl tail. A model was developed to describe both the requirements for electron transfer to A 1 and also previous results for electron transfer from A 1 − to the iron-sulfur centers (Biggins, J. (1990) Biochemistry 29, 7259–7264). When untreated PS I preparations were incubated with perdeuterated vitamin K 1 (DK 1 ) the endogenous K 1 was observed to exchange with DK 1 . The replacement rate was strongly dependent upon temperature (h-days at 4°C, min at 37°C) and upon illumination (min). Naphthoquinones lacking a long alkyl tail were unable to exchange with endogenous vitamin K 1 . Although no known physiological role exists for vitamin K 1 ejection from its A 1 binding site, the quinone appears to be somewhat labile. Direct exchange of vitamin K 1 with exogenously supplied quinones indicates that the PS I A 1 site might be a target for the design of new herbicides in green plants.

Peptides corresponding to the first 40 amino acids of beta amyloid peptide (beta 1-40) and the reverse sequence (beta 40-1) were synthesized, purified, and compared for their ability to aggregate and cause toxicity in vitro to human neuroblastoma cells (SH-SY5Y), as well as for effects following injection into young or aged rats. Aggregation of both peptides produced similar sedimentation velocity profiles and resulted in significant toxicity in vitro with no observable differences between beta 1-40 and beta 40-1. In addition, when injected into the cortex of young rats, beta 1-40 was more toxic than beta 40-1 although both resulted in significant lesions. However, in aged rats the two peptides resulted in lesions of similar size. Alz 50 staining and abnormal neurites were associated with both beta 1-40 and beta 40-1 lesions; however, no evidence of plaques or tangles was found in either age group. While both peptides were toxic in vitro, only beta 1-40 elicited Alz 50 staining of SH-SY5Y cells. Electron microscopic examination of beta 1-40 and beta 40-1 aggregates showed that beta 1-40 formed fibrillar structures whereas beta 40-1 resulted in amorphous particles. Thus, although both peptides were toxic to cultured cells and aged rats, the toxicities may have resulted from different mechanisms.

The protein portion of the reaction center (RC) complex is composed of three subunits: the intermembrane L and M chains, and the cytoplasmic H polypeptide. The cofactors are within the transmembrane region; they are related by approximate twofold symmetry as are the homologous L and M chains [1–4]. The cofactors consist of a bacteriochlorophyll dimer that is the primary electron donor, two bacteriochlorophyll monomers, two bacteriopheophytins, a non-heme iron atom, and two quinones which serve as the final electron acceptors.

The characteristic electron spin polarized electron paramagnetic resonance (ESP EPR) signal observed in photosystem I (PSI) has been previously assigned to a radical pair composed of the oxidized primary donor and a reduced vitamin K1. Under conditions in which Bottin, H. & Setif, P. [(1991), Biochim. Biophys. Acta 105, 331-336] proposed that A1 is doubly reduced, the ESP EPR signal was not observed. Therefore, the ESP EPR signal can be directly attributed to A-1, and vitamin K1 can be assigned as this PSI acceptor. The ESP EPR signal was partially restored by removal of the chemical reductants.