Reactions of VX, GB, GD, and HD with nanosize Al(2)O(3). Formation of aluminophosphonates.

Room-temperature reactions of VX, GB, GD, and HD with nanosize Al(2)O(3) (AP-Al(2)O(3)) have been characterized by (31)P, (13)C, and (27)Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH(3))OR](3), are generated which are identical to synthesized model compounds. Thus the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amount of the CH-TG sulfonium ion (12%), although some elimination of HCl is also observed (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addition of excess water results in the quantitative hydrolysis of sorbed HD to CH-TG. On AP-Al(2)O(3) dried to remove physisorbed water, (13)C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

Isolation and chemical analyses of nonfermented fiber fractions of oat hulls and cottonseed hulls.

The purpose of this study was to isolate, using both in situ and in vivo methodology, the nonfermented fiber fraction of oat hulls (OH) and cottonseed hulls (CSH) and to compare the concentrations of alkali-labile phenolic monomers, nitrobenzene oxidizable phenolic monomers, and neutral monosaccharides, as well as the cross polarization/magic angle spinning (CP/MAS) carbon-13 (13C) nuclear magnetic resonance (NMR) spectra, of the nonfermented fraction with the original OH or CSH. The in situ isolation procedure involved a 30-h ruminal pretreatment and an 8-h acid:pepsin pretreatment followed by 1 to 7 additional days of incubation in the rumen. Fractions not fermented in vivo were isolated from duodena, ileal, and fecal material obtained from a site and extent of digestion trial in which these byproducts were fed to sheep at 80% of the diet (as-fed basis) and they represented the sole source of dietary fiber. Based on nonfermented fraction composition, both in situ and in vivo, all components analyzed were degraded to some extent. Also, all components present in original byproduct material were present in both the in situ and in vivo nonfermented fractions. Based on NMR analysis, cellulose crystallinity did not change during either long-term in situ or in vivo fermentation. However, CSH cellulose was more crystalline than that of OH. The ADL content of OH and CSH was 6.1% and 19.4%, respectively, and very little (15%) of the ADL disappeared during either in situ or in vivo fermentation. Much of the p-coumaric and ferulic acid of OH, associated with the cell wall matrix as lignin-carbohydrate and phenolic-carbohydrate complexes, was recovered in the fermented fractions. Data are interpreted to indicate that lignin encrustation and cellulose crystallinity are factors affecting CSH fermentation. Lignin encrustation and the presence of lignin-carbohydrate/phenolic-carbohydrate complexes are factors that inhibit OH fermentation.

Comparison of the antimicrobial effectiveness of regular and fresh scent Clorox.

The antimicrobial properties of two different compositions of sodium hypochlorite were compared in a tube dilution study. Absorbent paper points were contaminated with Streptococcus faecalis or Candida albicans and exposed to 5.25% or 2.62% concentrations of "regular" or "fresh scent" sodium hypochlorite (Clorox) for periods ranging from 15 to 120 s. The points were then removed from the sodium hypochlorite solution, placed into a growth medium, incubated, and the presence or absence of growth recorded. Results showed that formulary changes involved in the manufacture of the "fresh scent" sodium hypochlorite had no apparent effect on its antimicrobial properties, as both compositions proved equally effective against the test organisms at each concentration evaluated.

Inhibitors of a rat brain enkephalin aminopeptidase.

Eight protease inhibitors of microbiological origin were examined as potential inhibitors of a homogeneous rat brain enkephalin aminopeptidase. Bestatin [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl]-L-leucine and analogs of bestatin having basic, acid, and other neutral amino acids substituted for the Leu residue exhibited inhibition constants ranging from 3.3 X 10(-5) to 8.3 X 10(-8) M. The best inhibitor had a positively charged amino acid (Lys) substituted for Leu. A series of phenylalanyl dipeptides were examined as substrates with the aminopeptidase. The amino acid residue on the carboxyl side of the peptide bond undergoing cleavage was varied systematically in the dipeptides to include neutral, acidic, and basic residues. Again, a positively charged amino acid (Arg) adjacent to the bond undergoing scission was kinetically preferred. These results may be used to design highly specific inhibitors of the enkephalin aminopeptidase.

Purification and characterization of an enkephalin aminopeptidase from rat brain.

Rat brain enkephalin aminopeptidase was purified to apparent electrophoretic homogeneity. Enzyme activity was monitored during the purification by using ([3,5-3H2]Tyr)-Met-enkephalin and Tyr-beta-naphthylamide as substrates. It was shown that the enzyme activities resulting in hydrolysis of the tyrosine residue of ([3,5-3H2]Tyr)Met-enkephalin and formation of beta-naphthylamine from Tyr-beta-naphthylamide copurified. The homogeneous enzyme had a specific activity of 10.5 mumol of beta-naphthylamide hydrolyzed min-1 mg-1. Hydrolysis of Met-enkephalin yielded the products L-tyrosine and the tetrapeptide Gly-Gly-Phe-Met. Subsequent removal of glycine from Gly-Gly-Phe-Met was not observed with the purified enzyme. The homogeneous aminopeptidase has an apparent molecular weight of 115000 on Sephadex G-200 and a molecular weight of 102000 as determined by electrophoresis in the presence of sodium dodecyl sulfate. The enkephalin-degrading enzyme had a pH optimum of 6.5-7.0 and exhibited maximal activity at 40 degrees C. Enzyme activity was inhibited by metal chelators, and it was found that 1 mol of Zn2+ was associated with 1 mol of enzyme (102000 Mr). The enzyme hydrolyzes various neutral and basic amino acid beta-naphthylamides but will not utilize acidic, D-amino acid, or N-terminal-blocked amino acid beta-naphthylamides as substrates.