Kinetic properties of soybean net photosynthetic CO(2) fixation and of the carboxylase and oxygenase activities of purified soybean (Glycine max [L.] Merr.) ribulose 1, 5-diphosphate carboxylase (EC 4.1.1.39) were examined as functions of temperature, CO(2) concentration, and O(2) concentration. With leaves, O(2) inhibition of net photosynthetic CO(2) fixation increased when the ambient leaf te...

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...

Reliable estimates of Michaelis constants (K(m)) and inhibitor constants may be obtained, in the absence of control over the amount of enzyme being added to any assay system, provided the following constraints are met. Michaelis-Menten kinetics are obeyed. Two rate measurements must be made with the same sample of enzyme: at low and high substrate concentration for determining K(m) or minus and...

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...

Microbial bioanodes were formed in pulp and paper effluent on graphite plate electrodes under constant polarization at -0.3 V/SCE, without any addition of nutriment or substrate. The bioanodes were characterized in 3-electrode set-ups, in continuous mode, with hydraulic retention times from 6 to 48 h and inlet COD from 500 to 5200 mg/L. Current densities around 4A/m(2) were obtained and voltamm...

The immobilization of catalase was carried out from enzyme solutions in acid (pH < 3.5) and alkaline (pH > 1 1 ) medium on two kinds of soot differing by the average size of the particles. Under these conditions the peroxidase-like activity of immobilized catalase in the oxidation of phenol has been studied. The effect of the initial concentration of the substrate on the rate of the process cat...

1. Inhibition by pyridine of reduction of NAD by ethanol in the presence of yeast alcohol dehydrogenase was studied at 25 degrees in 60mm-glycine buffer (K(+), pH9.3). 2. The apparent Michaelis constant for ethanol increases linearly and that for NAD increases non-linearly with pyridine concentration. 3. Rates, v, observed in the presence of pyridine are lower than the values calculated from th...

We have made experimental studies into the enzymatic hydrolysis of cellobiose within the temperature range of 40°C to 70°C at pH 4.9, by using b-1,4-glucosidase from Aspergillus niger. At 70°C there was significant enzyme deactivation, which could be fitted to a potential deactivation model with values of n equal to 1.09 and kd to 0.1564 (g/l) 20.09 min, whereas the rate of hydrolysis could be ...

Three pathways for phosphatidylcholine synthesis were assayed in castor bean (Ricinus communis var. Hale) endosperm. Phosphatidylethanolamine: S-adenosylmethionine methyl transferase occurred predominantly in the endoplasmic reticulum fraction, but some activity appeared in the mitochondria. Phosphorylcholine glyceride transferase occurred exclusively in the endoplasmic reticulum. The phosphory...

The electrogenicity and some molecular properties of the sarcoplasmic reticulum Ca2+ pump protein were studied by measuring steady-state Ca2+ pump currents. Ca2(+)-ATPase protein was solubilized from rabbit skeletal muscle sarcoplasmic reticulum membrane preparations and purified by liquid chromatography. The purified Ca(+)-ATPase molecules were reconstituted into proteoliposomes and then incor...