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...

A phytase (EC 3.1.3.8) with a high affinity for phytic acid was found in Aspergillus niger SK-57 and purified to homogeneity in four steps by using ion-exchange chromatography (two types), gel filtration, and chromatofocusing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme gave a single stained band at a molecular mass of approximately 60 kDa. The Michaelis con...

Real time monitoring of electrolyte resistance changes during hydrolysis of 4-nitrophenylphosphate (pNPP) by alkaline phosphatase (ALP) bound on paramagnetic-beads was performed into a small dielectric channel. The reaction kinetic fit with a non-competitive substrate-inhibition equation. Michaelis-Menten apparent constant, KM(app), was determined as 0.33±0.06mM and the maximum apparent rate, V...

The involvement of FMO in the N-oxygenation of CLZ was investigated by use of purified FMOs and human liver microsomes that contained the mean amount of immunoreactive FMO3 relative to other human liver microsomal preparations in a liver bank. In the microsomal preparation the involvement of FMO was indicated through enzyme inhibition by methimazole, heat inactivation, and protection against he...

242 words Introduction: 491 words Discussion: 1168 words Abbreviations: ARB, angiotensin receptor blocker; AM, azilsartan medoxomil; BNPP, bis-p-nitrophenylphosphate; CC, candesartan cilexetil; CES, carboxylesterase; CMBL, carboxymethylenebutenolidase homolog; Km, Michaelis constant; LC-MS/MS, liquid chromatography with tandem mass spectrometry; OM, olmesartan medoxomil; S9, This article has no...

An enzymatic assay system for nitrate employing the membrane-bound nitrate reductase (EC 1.7.99.4) of E. coli is described. Contrary to previous enzymatic assay systems, the present method is a kinetic one, i.e. the substrate, nitrate, is assayed by measuring the reaction rate of the nitrate reductase-catalyzed reaction. Based on the observation that the nitrate reductase-catalyzed reaction obe...

Absorption of L-methionine was measured in all parts of the human small intestine using transintestinal intubation and perfusion. In four normal subjects, adsorption was higher in the proximal than in the distal intestine. In two patients with nontropical sprue in relapse, there was a proximal zone of low absorption with higher absorption distally. In all parts of the small intestine, absorptio...

The parameters which characterize this equation, and which must ordinarily be estimated from the observed data, are ‘v,,,, the maximum initial velocity which is theoretically attained when the enzyme has been “saturated” by an infinite concentration of substrate, and K,, the Michaelis constant which is numerically equal to the concentration of substrate for half-maximal initial velocity. Since ...

We have found convincing evidence for the presence of Na-K-ATPase and high potassium (K) and low sodium (Na) concentrations in the erythrocytes of some dogs associated with hereditary high concentrations of erythrocyte glutathione and some amino acids. glutamate. glutamine. and aspartate. The Na-K-ATPase activity of the erythrocyte membranes of the dogs was about 3 times that of human erythrocy...

Errors in the numerical values of activation or normal enthalpies, entropies and free enthalpies calculated from Arrhenius or van't Hoff plots, respectively, are due to the neglect of equidimensionality in equations, or to inappropriate approximations. The logarithmization of dimensioned quantities should be avoided, which demands the use of relative concentrations if a change in mole number oc...