Author
Satoru Nagatoishi, Medical Device Development and Regulation Research Center, School of Engineering, The University of Tokyo Kouhei Tsumoto, Department of Bioengineering, School of Engineering, The University of Tokyo, Medical Device Development and Regulation Research Center, School of Engineering, The University of Tokyo
Keywords
Circular dichroism spectroscopy (CD), Hydrogen/deuterium exchange mass spectrometry (HDX-MS) Protein Structural analysis
Abstract
This study highlights the synergy between circular dichroism (CD) spectroscopy and hydrogen/deuterium exchange mass spectrometry (HDX-MS) in elucidating protein structure and dynamics. The CD provides rapid insight into secondary structures in solution. At the same time, HDX-MS offers site-specific information on protein conformation and dynamics by monitoring the exchange of backbone amide hydrogens with deuterium.
The authors present case studies where this combination is potent. First, analysis of the FIH-1 L340R mutant revealed local destabilization at the dimer interface, reducing its interaction with the Mint3 protein-validated by CD (loss of α-helicity) and HDX-MS (increased exchange in the C-terminal region). Second, mutations in single-domain antibodies, such as Y93A and E94A, significantly altered folding stability. Y93A broadly destabilized the structure, while E94A subtly enhanced thermal stability but altered indirectly the conformation of the CDR1 loop. These results demonstrate that the integrated use of CD and HDX-MS enables detailed, complementary analysis of protein structural changes, especially those induced by point mutations. This approach is increasingly valuable in protein engineering and therapeutic antibody development. Moreover, the authors believe that incorporating CD and HDX-MS data may further enhance structural prediction and functional interpretation as computational tools.