Kinetics of fibrinopeptide A release by human alpha-thrombin at low fibrinogen concentration allowed us to measure the specificity constant, i.e. kcat/Km, for the interaction between the enzyme and human fibrinogen. A study of the dependence of the ratio kcat/Km upon the viscosity of the medium revealed that fibrinogen acts as a 'sticky' substrate, or, in other words, as a substrate that dissoc...

Catalytic activity of catalase (CAT, EC 1.11.1.6), immobilized on carbon black NORIT and soot PM-100, with respect to decomposition of dibenzoyl peroxide (BPO) in non-aqueous media (acetonitrile and tetrachloromethane), was investigated with a quantitative UV-spectrophotometrical approach. Progress of the above reaction was controlled by selected kinetic parameters: the apparent Michaelis const...

and substrate are in direct contact, and the solubility of chlorpromazine therefore appears greater. These previous investigators have fitted data to a normaf Scatchard plot, though there are signs of the plots having been forced through the points at low concentrations. The present results, taken in conjunction with previous ones, indicate a close similarity between chlorpromazine binding to a...

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 ...

Physicochemical and immunologic properties of 6-aminolevulinate (ALA) dehydratase in human K562 erythroleukemia cells were examined. ALA dehydratase activity was found to increase in K562 cells after treatment with butyric acid or selenium oxide. Enzyme activity in untreated K562 cells was comparable to that in normal adult erythrocytes but was increased threeto six-fold in K562 cells treated w...

Physicochemical and immunologic properties of 6-aminolevulinate (ALA) dehydratase in human K562 erythroleukemia cells were examined. ALA dehydratase activity was found to increase in K562 cells after treatment with butyric acid or selenium oxide. Enzyme activity in untreated K562 cells was comparable to that in normal adult erythrocytes but was increased threeto six-fold in K562 cells treated w...

We present a model of an ATP-fueled molecular machine which push a polymer through a pore channel. The machine acts between two levels (workingwaiting), and the working one remains active for a fixed time giving a constant force. The machine activation rate can be put in relationship with the available ATP concentration in the solution, which gives the necessary energy supply. The translocation...