Unveiling the Intramolecular Thermodynamics of Multivalent Proteins: Exploratory Study on Engineered Protein Model

Multivalent interactions mediated by multidomain proteins are pivotal in numerous biological processes. However, the thermodynamic intricacies of the domain interactions within such complexes remain elusive. In this study, we employed surface plasmon resonance to explore the temperature-dependent kinetics of multidomain protein interactions across various valences from monomers to tetramers. Rigorous screening of protein-peptide binding pairs fused with discrete multivalent protein scaffolds facilitated the selection of candidates with minimal nonspecific interactions and suitable monomer binding kinetics that could be extended to higher valences. We developed a theoretical model to extract the thermodynamic quantities for both inter- and intramolecular interactions. By employing initial rate analysis, we could extract thermodynamic quantities describing complicated interactions between multivalent proteins. Our analysis provides novel insights into the thermodynamics of intramolecular interactions in multivalent protein complexes with implications for protein design and engineering.