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...

The temperature dependence of the activity and structure of the enzyme carbonic anhydrase was studied. The Arrhenius plot shows a jump which is seen usually in proteins with more than one subunit or with one subunit but more than one domain. Since carbonic anhydrase has only one subunit with one domain, the fine conformational changes of the protein motifs could only be detected through circula...

Lipids of mitochondrial membranes from hepatic cells of active ground squirrels apparently go through a phase change induced at approximately 23 degrees C similar to the phase change in mitochondria of homeotherms. This change was indicated by the activity of succinate oxidase from the isolated mitochondria exhibiting a nonintersecting discontinuous Arrhenius plot. This discontinuity in the Arr...

A soluble delipidized (Na + K)-stimulated ATPase was obtained from rabbit kidney outer medulla by the use of sodium deoxycholate. The activity of this enzyme was stimulated ZO-fold to an activity of 100 to 120 pmoles of Pi per mg of protein per hour by either phosphatidylserine or phosphatidylglycerol. The effect of the fluidity of the hydrocarbon region of the phospholipid bilayers on this re-...

A soluble delipidized (Na + K)-stimulated ATPase was obtained from rabbit kidney outer medulla by the use of sodium deoxycholate. The activity of this enzyme was stimulated ZO-fold to an activity of 100 to 120 pmoles of Pi per mg of protein per hour by either phosphatidylserine or phosphatidylglycerol. The effect of the fluidity of the hydrocarbon region of the phospholipid bilayers on this re-...

An approach for computing the correlations of species richness values obtained from nested and non-nested sampling schemes is described. The correlations obtained are used to construct species accumulation curves for the Carolina Vegetation Survey data set using the log Arrhenius, Gleason, and Arrhenius models. These models are then used to predict the richness at the 400 m2 scale, a value outs...

Thermally activated processes are characterized by two key quantities, activation energy (E(a)) and pre-exponential factor (nu(0)), which may be temperature dependent. The accurate measurement of E(a), nu(0), and their temperature dependence is critical for understanding the thermal activation mechanisms of non-Arrhenius processes. However, the classic 1D Arrhenius plot-based methods cannot una...

Methods for preparing native scallop sarcoplasmic reticulum vesicles, largely purified membranous scallop sarcoplasmic reticulum Ca2+-ATPase, and nonionic detergent-solubilized sarcoplasmic reticulum Ca2+-ATPase are described. The effect of a range of polyoxyethylene-based detergents on the solubilized Ca2+-ATPase was tested. Decaethylene glycol dodecyl ether (C12E10) supported the highest leve...

1. Glutaminase activity in frozen and thawed liver mitochondria was activated by NH4+, phosphate and HCO3-ions and also by ATP . 2. NH4+ and HCO3-ions decreased the requirement of the enzyme for phosphate. The activation by ATP was observed only in the presence of NH4+ or HCO3-ions. 3. In frozen-and-thawed mitochondria, the enzyme was loosely bound to the inner membrane, the Arrhenius plot show...

the use of accelerated temperature stability studies using the arrhenius relationship is routine for estimating the stability of a drug at room temperature. therefore, the acceleration method is used to determine the expiration date of dexamethasone aqueous formulation manufactured in iran. a high-performance liquid chromatography (hplc) method utilizing ultraviolet (uv) detection for dexametha...