Calorimetric analysis using DNA thermal stability to determine protein concentration

Area of Science:

• Biophysical Chemistry
• Molecular Biology
• Biochemistry

Background:

• Transition heat capacities (C_p) of globular proteins and DNA hairpins are nearly equivalent at equal concentrations.
• This equivalence is independent of DNA sequence, buffer salt composition, and melting temperature (T_m).

Approach:

• Investigated the equivalence of C_p values for DNA and proteins across varying conditions.
• Developed a calorimetric method utilizing a DNA hairpin standard for protein concentration determination.
• Compared calorimetric results with UV-Vis spectroscopy for both monomeric and multimeric proteins.

Key Points:

• The transition heat capacities of DNA and proteins exhibit remarkable equivalence.
• A novel calorimetric assay was established for quantifying protein concentrations using DNA standards.
• The method accurately determines monomeric protein concentrations, aligning with UV-Vis measurements.
• For multimeric proteins, the calorimetric method revealed higher concentrations than UV-Vis, indicating potential for detecting oligomeric states.

Conclusions:

• The equivalence of transition heat capacities provides a robust foundation for a new protein quantification technique.
• This calorimetric approach offers a sensitive and versatile alternative to traditional methods, particularly for complex biological samples.
• The observed discrepancies in multimeric protein quantification highlight the method's potential for characterizing protein assembly states.