Microcalorimetry

Microcalorimetry and UV-vis spectroscopy were used to conduct thermodynamic and kinetic investigations of the scission of calf thymus DNA catalyzed by bleomycin A5 (BLM-A5) in the presence of ferrous ion and oxygen. The molar reaction enthalpy for the cleavage, the Michaelis– Menten constant for calf thymus DNA and the turnover number of BLM-A5 were calculated by a novel thermokinetic method for an enzyme-catalyzed reaction to be )577 ± 19 kJÆmol)1, 20.4 ± 3.8 lM and 2.28 ± 0.49 · 10)2 s)1, respectively, at 37.0 °C. This DNA cleavage was a largely exothermic reaction....

9p system191 01-06-2013 32 4   Download

The enzymes pyruvate decarboxylase (E1) and dihydro-lipoyl dehydrogenase (E3) bind tightly but in a mutually exclusive manner to the peripheral subunit-binding domain (PSBD) of dihydrolipoyl acetyltransferase in the pyruvate dehydrogenase multienzyme complex of Bacillus stearo-thermophilus.

9p fptmusic 12-04-2013 44 2   Download

Staphylococcalnuclease is a single domain protein with 149 amino acids. It has no disulfide bonds, which makes it a simple model for the study of pro-tein folding. In this study, 20 mutants of this protein were generated each with a single base substitution of glycine for negatively charged glutamic acid or aspartic acid. Using differential scanning microcalorimetry in ther-mal denaturation experiments, we identified two mutants, E75G and E129G, having approximately 43% and 44%, respectively, lowerDHcal values than the wild-type protein....

8p fptmusic 11-04-2013 47 3   Download

3-Phosphoglycerate kinase (PGK) is a typical two-domain hinge-bending enzyme with a well-structured interdomain region. The mechanism of domain–domain interaction and its regulation by substrate binding is not yet fully understood. Here the existence of strong cooperativity between the two domains was demonstrated by following heat transitions of pig muscle and yeast PGKs using differential scanning microcalorimetry and fluorimetry.

19p awards 06-04-2013 55 4   Download