The hypothesis that phase transitions originate from some topological change of the critical level hypersurface of the potential energy receives direct evident support by our study of the Bishop-Peyrard model of DNA thermal denaturation.

Chimeric enzymes were constructed to elucidate the differences in physicochemical properties of two related bacterial RNases, barnase and binase. Chimeras (Ba26Bi, Ba73Bi, Ba26Bi73Ba and Bi73Ba) contain six to thirteen residue substitutions relative to barnase, which are beyond the active site. The catalytic activity of RNases toward GpU, GpC and poly(I), as well as conformational distinctions ...

Thermal denaturation profiles were used to quantitate the destabilizing activity of five classes of polyanions in an effort to explain previously reported differences in activity among apparently similar polymers. This physical assay for polyanion action on chromatin is free of the biochemical complications associated with template assay systems. Most polyanions tested caused a thermal destabil...

Fusion of modified LDL in the arterial wall promotes atherogenesis. Earlier we showed that thermal denaturation mimics LDL remodeling and fusion, and revealed kinetic origin of LDL stability. Here we report the first quantitative analysis of LDL thermal stability. Turbidity data show sigmoidal kinetics of LDL heat denaturation, which is unique among lipoproteins, suggesting that fusion is prece...

We compared the thermal aggregation properties of two isoforms of the isolated myosin head (myosin subfragment 1, S1) containing different "essential" (or "alkali") light chains, A1 or A2. Temperature dependencies for the aggregation of these two S1 isoforms, as measured by the increase in turbidity, were compared with the temperature dependencies of their thermal denaturation obtained from dif...

Glucose oxidase (GOX; beta-d-glucose:oxygen oxidoreductase) from Aspergillus niger is a dimeric flavoprotein with a molecular mass of 80 kDa/monomer. Thermal denaturation of glucose oxidase has been studied by absorbance, circular dichroism spectroscopy, viscosimetry, and differential scanning calorimetry. Thermal transition of this homodimeric enzyme is irreversible and, surprisingly, independ...

the thermal denaturation of α-amylase from bacillus amyloliquefaciens has been investigated in the presence and absence of sodium dodecyl sulphate (sds) over the temperature range (293-373) k in 20 mm sodium phosphate buffer, ph 6.9, using temperature scanning spectroscopy. the presence of sds caused the destabilization of α-amylase resulting in a decrease in the temperature of unfolding with a...

BACKGROUND The stability of a virus-like particle (VLP) is an important consideration for its use in nanobiotechnology. The icosahedral capsid of the RNA bacteriophage PP7 is cross-linked by disulfide bonds between coat protein dimers at its 5-fold and quasi-6-fold symmetry axes. This work determined the effects of these disulfides on the VLP's thermal stability. RESULTS Measurements of the t...

Cold denaturation is a general property of globular proteins, but it is difficult to directly characterize because the transition temperature of protein cold denaturation, T(c), is often below the freezing point of water. As a result, studies of protein cold denaturation are often facilitated by addition of denaturants, using destabilizing pHs or extremes of pressure, or reverse micelle encapsu...