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Organophosphorus (OP) insecticides and nerve agents that contain P-S bond are relatively more resistant to enzymatic hydrolysis. Purified phenol oxidase (laccase) from the white rot fungus Pleurotus ostreatus (Po) together with the mediator 2,2P-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) displayed complete and rapid oxidative degradation of the nerve agents VX and Russian VX (RVX) and the insecticide analog diisopropyl-Amiton with specific activity: k sp = 2200, 667 and 1833 nmol min 3I mg 3I , respectively (pH 7.4, 37³C). A molar ratio of 1:20 for OP/ABTS and 0.05 M phosphate at pH 7.4 provided the highest degradation rate of VX and RVX. The thermostable laccase purified from the fungus Chaetomium thermophilium (Ct) in the presence of ABTS caused a 52-fold slower degradation of VX with k sp = 42 nmol min 3I mg 3I . The enzymatic biodegradation products were identified by QI P-NMR and GC/MS analysis.z 1998 Federation of European Biochemical Societies.

Diethyl pyrocarbonate, an enzyme inhibitor and bactericidal agent, reacts in aqueous solution with purine ribonucleosides to form products in which the imidazole ring has been opened, e.g., compound 2 from adenosine, as previously reported, and compound 4, 2-amino-5-carbethoxyamino-4-hydroxy-6-V-ribofuranosylaminopyrimidine, from guanosine. Unlike adenine, which does react, the free base guanine was not modified under the conditions employed. Cytosine and the "minor base" 5-hydroxymethylcytosme react with diethyl pyrocarbonate in aqueous solution to give respectively 1 -carbethoxycytosine (9) and an unstable compound which appears to be the 1-carbethoxylated derivative 11. The ribonucleoside cytidine reacted under the same conditions to give V4-carbethoxycytidine (13). Uracil and thymine, in slightly basic aqueous media, give closely related ring-substituted products 1-carbethoxyuracil (15) and 1 -carbethoxythymine (17). The ribonucleosides uridine and ribothymidine, by contrast, react in slightly basic solution to form unstable products which spectral data suggest to be 3-carbethoxyuridine (19) and 3-carbethoAyribothymidine (21). Pseudouridine C, a modified nucleoside found

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With the use of a multisector ion/surface scattering mass spectrometer, the benzoyl cation, C6H5CO+, is mass- and energy-selected and then made to collide at hyperthermal energies (i.e., <100 eV) with an HO-terminated self-assembled monolayer (HO−SAM) surface. Fourier transform infrared external reflectance spectroscopy (FTIR-ERS) indicates that this ion/surface collision results in C−O bond formation at the surface, producing the terminal benzoate. The covalent modification of the hydroxyl surface is further substantiated by subsequent ion/surface scattering experiments, in which 70-eV CF3 + ions are used as projectiles. Chemically sputtered ions resulting from the collision of the CF3 + ion with the ion-modified surface include the reagent ion, C6H5CO+, and its fragments, C6H5 + and C4H3 +. The same chemically sputtered ions are observed when a C6H5CO2-terminated self-assembled monolayer surface is similarly analyzed using CF3 +. Using collisions of CF3 + to analyze a series of mixed SAM surfaces (prepared from varying amounts of the HO-terminated disulfide and the C6H5CO2-terminated disulfide), calibration of the chemically sputtered products reveals that a 2-h modification with the benzoyl cation results in ca. 15% reaction yield (i.e., 15% of the surface groups are converted to products). The reaction efficiency (i.e., fraction of gas-phase cations converted to surface-bound products) is roughly estimated as 75%, the first ion/surface reaction efficiency to be reported. Analogous surface transformations are achieved using CH3CO+ and C6H5CH2 +.