The alkaline pH range over which the double stranded circular DNA of the replicative form of the bacterial virus, 4x174, is reversibly denatured has been determined in order to specify accurately the conditions for a preparative procedure for this DNA based on selective alkali denaturation. The denaturation remains entirely reversible to pH 12.6 at an ionic strength of about 0.25 over a range i...

Thermal denaturation of p-Iactoglobulin type B in the absence and pteNcno: of g arious concentrations oftrehalo5e, sucrose and sork toles sugar osmolytes and twlyols were nuyoured hy monitoring changes in theabsorption coefficients at pH 2.0. These measurements gave aliss, or I. mpdpDint of denaturation), Al-fis(enthalpy change at Ty). and ACp (consttun-pressure heal capaciit eh.iltgtii under a...

1. Preparations of rabbit serum albumin, dialysed against rabbit plasma, were incubated at temperatures in the range 3949°C at pH 7.3 and pH values in the range 7.2-8.0 at 43°C. 2. Denaturation of the rabbit albumin was studied by measuring (a) its susceptibility to tryptic hydrolysis and (b) catabolic rates in rabbits. 3. The rabbit albumin was demonstrated to denature by both criteria. 4. Ass...

Differential scanning microcalorimetry was used to assess the conformational stability of muscle lactate dehydrogenase (M4-LDH) from skeletal muscle of Misgurnus fossilis (loach) fishes adapted to low (the “cold” enzyme) and high (the “warm” enzyme) environmental temperatures. It was found that the denaturation temperature Td was the same for both forms of lactate dehydrogenase, whereas the den...

Modal DNA (ploidy) and sensitivity of DNA in situ to denaturation by acid have been analyzed by flow cytometry of 10 colorectal adenomas and 35 adenocarcinomas; 39 normal mucosa samples served as controls. A new method was developed to denature DNA in chromatin of the freshly isolated, intact, and unfixed individual cell nuclei from surgically resected material. The sensitivity of DNA denaturat...

The reversible folding and unfolding of barley chymotrypsin inhibitor 2 (CI2) appears to be a rare example in which both equilibria and kinetics are described by a two-state model. Equilibrium denaturation by guanidinium chloride and heat is completely reversible, and the data can be fitted to a simple two-state model involving only native and denatured forms. The free energy of folding in the ...

Thermal stability of the pore-forming domain of colicin A was studied by high sensitivity differential scanning calorimetry and circular dichroism spectroscopy. In the pH range between 8 and 5, the thermal denaturation of the protein in solution occurs at 66-69 degrees C and is characterized by the calorimetric enthalpy of approximately 90 kcal/M. At pH below 5, there is a rapid pH-dependent de...