DNA Framework Programmed Conformational Reconstruction of Antibody Complementary Determining Region

The conformation of complementary determining region (CDR) is crucial in dictating its specificity and affinity for binding with an antigen, making it a focal point in artificial antibody engineering. Although desirable, programmable scaffolds that can regulate the conformation of individual CDRs with nanometer precision are still lacking. Here, we devise a strategy to program the CDR conformation by anchoring both ends of a free CDR loop to specific sites of a DNA framework structure. This method allows us to define the span of a single CDR loop with an ∼2 nm resolution. Using this approach, we create a series of DNA framework based artificial antibodies (DNFbodies) with varied CDR loop spans, leading to different antibody-antigen binding affinities. We find that an optimized single CDR loop (∼2.3 nm span) exhibits ∼3-fold improved affinity relative to natural antibodies, confirming the critical role of the CDR conformation. This study may inspire the rational design of artificial antibodies.