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Elevated hydrostatic pressure has been used to increase catalytic activity and thermal stability of alpha-chymotrypsin (CT). For an anilide substrate, characterized by a negative value of the reaction activation volume (DeltaV( not equal)), an increase in pressure at 20 degrees C results in an exponential acceleration of the hydrolysis rate catalyzed by CT(More)
The kinetics of electron-transfer involved in reactions of reduction of 2,6-dichlorophenol indophenol and Fe(CN)3-(6) by L-ascorbic acid and reduction of ferric cytochrome c by both L-ascorbic acid and reduced hydroxylamine oxidoreductase were studied as a function of three parameters: ionic strength, pressure (1-2000 bar) and temperature (4-20 degrees C)(More)
The heat- and pressure-induced unfolding of the glycosylated and unglycosylated forms of mature carboxypeptidase Y and the precursor procarboxypeptidase Y were analysed by differential scanning calorimetry and/or by their intrinsic fluorescence in the temperature range of 20-75 degrees C or the pressure range of 0.1-700 MPa. Under all conditions, the(More)
The effect of hydrostatic pressure on the unfolding of trypsin was studied by fluorescence spectroscopy under pressure from 1 to 7000 bar. It was found that, at pH 3.0 or pH 7.3, a stable partly denatured state of trypsin was obtained when the applied pressure was about 6.5 kbar. This transient denatured state did not show any enzymatic activity and was(More)
The pressure denaturation of trypsin from bovine pancreas was investigated by fluorescence spectroscopy in the pressure range 0. 1-700 MPa and by FTIR spectroscopy up to 1000 MPa. The tryptophan fluorescence measurements indicated that at pH 3.0 and 0 degrees C the pressure denaturation of trypsin is reversible but with a large hysteresis in the(More)
A tunable fourth derivative UV absorbance method based on a variable spectral shift has been developed and compared to the Savitzky-Golay method and the analytical derivative. The parameters of the method were optimised for the analysis of the UV absorbance spectra of the aromatic amino acids to quantify the effect of decreasing solvent polarity on their(More)
New Zealand White rabbits were treated with rifampicin at a dose of 50 mg/kg for 4 days. The total amount of microsomal hepatic cytochrome P-450 was not modified in treated, with respect to control, animals. However, further studies involving SDS-PAGE analysis, monooxygenase activity measurements and radial immunodiffusion assays indicated that rifampicin(More)