Origins of fine structure in DNA melting curves.

With the help of the one-dimensional random Potts-like model, we study the origins of fine structures observed on differential melting profiles of double-stranded DNA. We theoretically assess the effects of sequence arrangement on DNA melting curves through the comparison of results for random, correlated, and block sequences. Our results re-confirm the smearing out of the fine structure with the increase in chain length for all types of sequence arrangements and suggest that the fine structure is a finite-size effect.

DNA-based assay for calorimetric determination of protein concentrations in pure or mixed solutions.

It was recently reported that values of the transition heat capacities, as measured by differential scanning calorimetry, for two globular proteins and a short DNA hairpin in NaCl buffer are essentially equivalent, at equal concentrations (mg/mL). To validate the broad applicability of this phenomenon, additional evidence for this equivalence is presented that reveals it does not depend on DNA sequence, buffer salt, or transition temperature (Tm). Based on the equivalence of transition heat capacities, a calorimetric method was devised to determine protein concentrations in pure and complex solutions.

Calorimetric analysis using DNA thermal stability to determine protein concentration.

It was recently reported for two globular proteins and a short DNA hairpin in NaCl buffer that values of the transition heat capacities, and , for equal concentrations (mg/mL) of DNA and proteins, are essentially equivalent (differ by less than 1%). Additional evidence for this equivalence is presented that reveals this phenomenon does not depend on DNA sequence, buffer salt, or T. Sequences of two DNA hairpins were designed to confer a near 20°C difference in their T's.

Equivalence of the transition heat capacities of proteins and DNA.

It has been reported for many globular proteins that the native heat capacity at 25 °C, per gram, is the same. This has been interpreted to indicate that heat capacity is a fundamental property of native proteins that provides important information on molecular structure and stability. Heat capacities for both proteins and DNA has been suggested to be related to universal effects of hydration/solvation on native structures.

Ligand binding constants for human serum albumin evaluated by ratiometric analysis of DSC thermograms.

This paper describes an expanded application of our recently reported method (Eskew et al., Analytical Biochemistry 621,1 2021) utilizing thermogram signals for thermal denaturation measured by differential scanning calorimetry. Characteristic signals were used to quantitatively evaluate ligand binding constants for human serum albumin.