A comparative study was performed on the conformational stabilities of trypsin and α-chymotrypsin. At 45oC, trypsin was most stable at pH 3, while the highest stability of αchymotrypsin was observed at pH 5. With both ester and amide substrates, trypsin displayed activation at pH 3. In the case of α-chymotrypsin, activation was detected at pH 5 only with the amide substrate. The time curves of ...

The reversible denaturation of Escherichia coli alkaline phosphatase (AP) was followed by monitoring changes in enzymatic activity as well as by measurements of the time-resolved room temperature phosphorescence from Trp 109. It is well known that the denaturants, ethylene diamine tetraacetic acid (EDTA), acid and guanidine hydrochloride (GdnHCl) inactive AP by different mechanisms as reflected...

Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to monitor changes in the secondary structure and thermal stability of beta-lactoglobulin A and B in the presence of sodium dodecyl sulphate (SDS), N-ethylmaleimide (NEM), urea and cysteine. An increase in the thermal stabilities of both proteins was noted in the presence of 10 mM-SDS. In the pr...

Thermal denaturation of protonated polynucleotides is accompanied by a change in protonation [l-5] . The thermal transition at a given pH can thus be directly related to the pk’ of the proton-induced structural transition at a given temperature. For poly (A’).poly (A+) a strict relationship has been shown to hold over a large range of conditions [4-61. In fig. 1 the results in the literature an...

Partial renaturation of urea-denatured bovine pancreatic ribonuclease by polyanions such as phosphate and polyphosphates, as well as by nucleotides, has been observed by Sela, Anfinsen, and Harrington (1). The finding that the velocities of denaturation and renaturation of ribonuclease may be separately and easily measured (2) prompted us to reinvestigate by kinetic methods the manner by which ...

The heat induced conformational and structural changes of glucose oxidase from Aspergillus niger at pH 5.0 and 4.0 were investigated using fluorescence spectroscopy. Experimental studies were conducted in buffer solution in the 25°C70°C temperature range at constant time. At both pH values, the phase diagram was linear, indicating the presence of two molecular species induced by thermal treatme...