A self-assembled supramolecular complex is reported to catalyze alkyl-alkyl reductive elimination from high-valent transition metal complexes [such as gold(III) and platinum(IV)], the central bond-forming elementary step in many catalytic processes. The catalytic microenvironment of the supramolecular assembly acts as a functional enzyme mimic, applying the concepts of enzymatic catalysis to a ...

In an in vitro study, the cytochrome P-450 3A (CYP3A)-dependent metabolism and drug interactions of the 3-hydroxy-3-methylglutaryl-Co A reductase inhibitors lovastatin and pravastatin were compared. Lovastatin was metabolized by human liver microsomes to two major metabolites: 6'beta-hydroxy [Michaelis-Menten constant (Km): 7.8 +/- 2.7 microM] and 6'-exomethylene lovastatin (Km,10.3 +/- 2.6 mic...

Purified Helicobacter pylori urease displayed a sigmoid curve in the plot of velocity versus [S] at urea concentrations less than 0.1 mM. Under conditions where preservatives, glycerol, or polyethylene glycol (PEG), were added to the enzyme reaction, the substrate hydrolysis was consistent with Michaelis-Menten kinetics, with a Km of 0.21+/-0.06 mM and a Vmax of 1200+/-300 micromol min(-1) mg(-...

ER aminopeptidase 1 (ERAP1) customizes antigenic peptide precursors for MHC class I presentation and edits the antigenic peptide repertoire. Coding single nucleotide polymorphisms (SNPs) in ERAP1 were recently linked with predisposition to autoimmune disease, suggesting a link between pathogenesis of autoimmunity and ERAP1-mediated Ag processing. To investigate this possibility, we analyzed the...

ABSTRACT. Organic-inorganic hybrid nanoflowers method with unique properties are preferred than conventional immobilization methods for the past decade. Hereemoglobin-based material (HbNFs@Cu) was synthesized under different experimental conditions (pH 5.0-9.0 and 0.01-0.50 mgmL-1 of hemoglobin) obtaining a size 9-10 µm. The encapsulation percentage weight yield HbNFs@Cu were determined as 100%...

Np, for NPP Nec, Net ecosystem carbon exchange, as measured by micrometeorologists NB, Net biome productivity Gp, Gross primary productivity Jpmax, maximum flux density of canopy photosynthesis Reco, ecosystem respiration Rplant, plant respiration Rauto, soil autotrophic respiration Rhetero, soil heterotrophic respiration Rsoil, total soil respiration Ea,actual evaporation Ep, potential evapora...

The reactivity of tyrosinase adsorbed on nanogold bound with 4,4'-bis(methanethiol)biphenyl monolayer self-assembled on a gold disk with catechol in a dipolar aprotic solvent, acetonitrile (AN), was studied by cyclic voltammetric and amperometric methods. Tyrosinase exhibited characteristics of a Michaelis-Menten kinetic mechanism. The tyrosinase attached to the nanogold continued to react with...

Induced and constitutive microsomal enzymes of mouse and hamster lungs catalyze both the hydroxylation of benzo(alpha)pyrene and reactions that lead to its irreversible binding to macromolecules. For mouse and hamster, the induced lung hydroxylases have Km values of 1.10 and 0.52 muM, respectively. The induced hydroxylases are strongly inhibited by 7,8-benzoflavone and are stimulated by cyclohe...

A pharmacokinetic model was constructed to describe the absorption, distribution, and metabolic clearance of N-nitrosodimethylamine. The model is composed of two compartments, total body water and the liver, which are linked by blood flow. Metabolic clearance is presumed to occur only in the liver. Liver clearance kinetics was determined with isolated perfused livers. Clearance appeared to obey...