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 ...

Catalytic isomerization of glucose to fructose by immobilized glucose isomerase in an aqueous-ethanol medium was studied. Using Michaelis-Menten equation and Haldane relationship, the main kinetic parameters were determined: Kmf, Vmf, Kmr, Vmr. By comparing the aqueous-ethanol medium with an aqueous solution, the measured values of Kmr and Kmf were increased in the aqueous-ethanol solution, whi...

where E denotes a molecule of the enzyme phosphodiesterase (PDE), X1 denotes a molecule of c-di-GMP and P is the product of this reaction, pGpG. Here, we made a quasi steady-state assumption for the formation of the E:X1-complex. This makes the product formation the rate limiting step, yielding the maximal catalytic velocity Vmax = (e + ex1) · k cat and the Michaelis-Menten constant Km = (k PDE...

We study chemical reactions with complex mechanisms under two assumptions: (i) intermediates are present in small amounts (this is the quasi-steady-state hypothesis or QSS) and (ii) they are in equilibrium relations with substrates (this is the quasiequilibrium hypothesis or QE). Under these assumptions, we prove the generalized mass action law together with the basic relations between kinetic ...

For enzymatic progress curves conforming to the Michaelis–Menten mechanism (E + S ES → E + P) under the experimental conditions where the substrate concentration is at least several times smaller than the Michaelis constant, the minimal fitting model cast as a system of numerically integrated differential equations is the simple ‘hit-and-run’ mechanism, E + S → E + P. The best-fit value of sing...

The kinetics of the action of fumarase on L-malate and fumarate were investigated at constant ionic strength. This was done to evaluate reports that fumarase follows simple Michaelis-Menten kinetics. However, when pH, buffer concentration and ionic strength are all maintained at constant values, the Lineweaver-Burk plots exhibit pronounced downward curvature, characteristic of negative kinetic ...

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...

Glucose is the major substrate that sustains normal brain function. When the brain glucose concentration approaches zero, glucose transport across the blood-brain barrier becomes rate limiting for metabolism during, for example, increased metabolic activity and hypoglycemia. Steady-state brain glucose concentrations in alpha-chloralose anesthetized rats were measured noninvasively as a function...