dose-dependent pharmacokinetic of phenytoin necessitates the estimation of the maximum rate of metabolism (vm) and the michaelis-menten constant (km) in a concerned population. the aim of this study was to determine the pharmacokinetic parameters of phenytoin in a sample of iranian patients to optimize the antiepileptic pharmacotherapy. fourty patients who received a constant dose of phenytoin ...

in present study, the kinetic parameters of purified trypsin from pyloric caeca of common kilka (c.cultriventris caspia) were measured using the amidolytic (bapna) and esterolytic (tame) substrates. the results of the kinetic comparison between bapna and tame substrates showed that kinetic parameters including maximum velocity (vmax), catalytic constant (kcat) and catalytic efficiency (kcat/km)...

The electrocatalytic oxidation of vitamin B6 (pyridoxine hydrochloride) was demonstrated on a Nafion/lead ruthenate pyrochlore modified electrode (designated as NCME) by cyclic voltammetry. The catalytic activity of vitamin B6 was explored in terms of the higher oxidation state of ruthenium species, i.e., Py-Ru/Ru in the pyrochlore network (Py). The mediated mechanism was derived by Michaelis-M...

Enzyme kinetics are usually described by the Michaelis-Menten equation, where the time-dependent decrease of substrate (-dS/dt) is a hyperbolic function of maximal velocity (Vmax), Michaelis constant (Km), and amount of substrate (S). Because the Michaelis-Menten function in its most general meaning requires an assumption of steady-state, it is less curvilinear than true enzyme kinetics. A satu...

A biodegradable polyester resin was polymerized from N-benzyloxycarbonylL -glutamic acid and ethylene glycol. Rhizopus delemar lipase was used as a biocatalyst for the rupture of ester bonds during the hydrolysis studies. Depolymerization was observed to followa Michaelis–Menten mechanism, with the maximumrate of monomer formation dP/dtmax = 1.12 x 10-8 mol/s and the rate constant Km x 2.03 x 1...

The effect of hypothermia on the in vivo pharmacokinetics of midazolam was evaluated, with a focus on altered metabolism in the liver and binding to serum proteins. Rat primary hepatocytes were incubated with midazolam (which is metabolized mainly by CYP3A2) at 37, 32 or 28 °C. The Michaelis-Menten constant (Km) and maximum velocity (Vmax) of midazolam were estimated using the Michaelis-Menten ...

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...

Abstract. Ectoenzymatic activity, prokaryotic heterotrophic abundances and production were determined in the Mediterranean Sea. Sampling was carried out sub-surface, deep chlorophyll maximum layer (DCM), core of Levantine intermediate waters deeper part mesopelagic layers. Michaelis–Menten kinetics assessed using a large range concentrations fluorogenic substrates (0.025 to 50 µM). As consequen...

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...