Adenosine triphosphatase (ATPase) activities of sonically prepared submitochondrial particles of rat liver and Morris Hepatoma 3924A were compared as a function of changes in temperature. On Arrhenius plots, a discontinuity at 18 degrees was observed for the rat liver mitochondrial ATPase, while the hepatoma mitochondrial ATPase revealed a discontinuity at 20.4 degrees. Values for energy of act...

There are many products, including hard drives, which require trace amounts, on the order of several milligrams, of lubricants for proper operation. The following study investigated the evaporation rates of pump oil and several alkanes, which have a wide range of applications. Both static and dynamic temperature tests were conducted. The rate of evaporation of the test specimen was determined a...

Elastic models imply that the energy expended for a flow event in ultra-viscous matter coincides with the elastic work required for deforming and re-arranging the environment of the moving entity. This is quite promising for explaining the strong non-Arrhenius behavior of dynamic quantities of fragile super-cooled liquids. We argue that the activation volume obtained from dielectric relaxation ...

A method for estimating the activity of bacterial signal peptidase I (SPase I) was used to determine its activation energy (E[act]). Pro-OmpA-nuclease A, a hybrid secretory precursor, was purified to homogeneity under denaturing conditions and used as a substrate. This substrate was used to determine the activity of SPase I at different temperatures. The results show that the conformation of th...

The emission from the acidic form of the green fluorescence protein (GFP) changes with increasing time and temperature from t-1/2 to t-3/2 asymptotics. It is shown that a model of proton diffusion along a one-dimensional hydrogen-bond network within the protein, with a switch (Thr203) allowing for proton escape, explains the data quantitatively. From a comparison of the model with experiment, w...

The GTPase superfamily of enzymes that hydrolyze GTP have a number of conserved sequence regions (the so-called “Gmotifs”), and several of the subfamilies also require catalytic activation by specific GTPase-activating proteins. In the translational GTPases involved in protein synthesis, this activating function is instead accomplished by their interaction with the ribosome. Despite these simil...

Abstract A detailed kinetic modeling of the noncatalytic processes thermal pyrolysis and steam carbon dioxide reforming methane revealed almost completely identical kinetics conversion in these processes. This suggests that, temperature range 1400–1800 K, initial stage all is its pyrolysis. The results agree well with experimental data on For examined, Arrhenius expressions (pre-exponential fac...

In order to describe the relationship between lipid dynamics and enzyme function in endoplasmic reticulum membranes of the adrenal cortex, a study of temperature dependence of the 3P-hydroxysteroid dehydrogenase activity has been carried out at three different pH values, in relation to the change of the rotational motion of the membrane lipids. At pH 8.5, corresponding to the highest value of t...

2014 We measured the depolarized Rayleigh light scattering by water from 80°C down to 17°C. The spectra obtained could be analysed into two lines, a broad and a sharp one. From the sharp line we deduced a relaxation time which can be interpreted as a reorientational time due to rotations. The broad line gives a relaxation time which is Arrhenius temperature dependent, with an activation energy ...

The rate of cyclohexane photo-catalytic oxidation to cyclohexanone over anatase TiO(2) was studied at temperatures between 23 and 60 °C by in situ ATR-FTIR spectroscopy, and the kinetic parameters were estimated using a microkinetic model. At low temperatures, surface cyclohexanone formation is limited by cyclohexane adsorption due to unfavorable desorption of H(2)O, rather than previously prop...