Acid or base concentrations can be determined by performing an acid-base titration with OHor H+ ions, coulometricaliy generated by the electrolysis of water at a noble metal actuator electrode. This can be done very rapidly if the actuator electrode is in close proximity to an ISFET which is used as the indicator electrode to detect the equivalence point in the titration curve. In order to rest...

foot and mouth disease (fmd) is the most contagious disease of cloven-hoofed animals, causingsignificant economical losses in livestock animals. in this study fmd virus type a87/irn was cultured andmultiplied on bhk21 cells. the fmd virus was titrated by the tissue culture infection dose50 method(tcid50 /ml), the virus titration was 107.5.. the fmd virus samples were irradiated and inactivated ...

Thiol:disulfide oxidoreductases have a CXXC motif within their active sites. To initiate the reduction of a substrate disulfide bond, the thiolate form of the N-terminal cysteine residue (CXXC) of this motif performs a nucleophilic attack. Escherichia coli thioredoxin [Trx (CGPC)] is the best characterized thiol:disulfide oxidoreductase. Previous determinations of the active-site pKa values of ...

The effect of pH on steady state kinetic parameters for the yeast alcohol dehydrogenase-catalyzed reduction of aldehydes and oxidation of alcohols has been studied. The oxidation of p-CH3 benzyl alcohol-l, l-h2 and -l,l-dz by NAD+ was found to be characterized by large deuterium isotope effects (&J&n = 4.1 f 0.1) between pH 7.5 and 9.5, indicating a rate-limiting hydride transfer step in this p...

The ionization behavior of cholic acid, deoxycholic acid, and chenodeoxycholic acid in a variety of physiologically important molecular environments was studied using 13C NMR spectroscopy. The apparent pKa of the carboxyl group was determined from titration curves obtained from the dependence of the carboxyl carbon chemical shift on pH. Using 90% 13C isotopic substitution of the carboxyl carbon...

The hammerhead ribozyme undergoes a well-defined two-stage conformational folding process, induced by the binding of magnesium ions. In this study, we have used isothermal titration calorimetry to analyze the thermodynamics of magnesium binding and magnesium ion-induced folding of the ribozyme. Binding to the natural sequence ribozyme is strongly exothermic and can be analyzed in terms of seque...

The effect of pH on steady state kinetic parameters for the yeast alcohol dehydrogenase-catalyzed reduction of aldehydes and oxidation of alcohols has been studied. The oxidation of p-CH3 benzyl alcohol-l, l-h2 and -l,l-dz by NAD+ was found to be characterized by large deuterium isotope effects (&J&n = 4.1 f 0.1) between pH 7.5 and 9.5, indicating a rate-limiting hydride transfer step in this p...

Human carbonic anhydrase B loses enzymatic activity as it undergoes an irreversible conformational change near pH 4 (1). Riddiford (2) further found that seven of the eleven histidyl groups, which are unreactive in the native protein, become titratable during this change. Also, five or six of the eight tyrosyl groups do not ionize freely and reversibly in the native protein (2, 3). Human carbon...