Positive charge in the complementarity-determining regions of synthetic
nanobody-Fc fusion prevents aggregation
Abstract
In the past, specificity and affinity were the priority for synthetic
antibody library. However, therapeutic antibodies need good stability
for medical use. Through carefully adjust the chemical diversity in
CDRs, one hopes to design a synthetic antibody library with good
developability. Here we thoroughly analyzed 296 nanobody sequences and
structures, constructed a fully-functional synthetic nanobody library,
evaluated the relationship between aggregation and isoelectric point,
and found that high-pI nanobodies were more resistant to aggregation
than low-pIs. As we used the same framework for constructing the
library, CDRs charge played a crucial role in mediating nanobody
aggregation. We also analyzed the theoretical pI of 296 nanobodies from
PDB, about 75% had basic pI, only 25% were acidic. Those results
provided useful guidelines for designing next-generation synthetic
nanobody libraries and for identifying potent and safe nanobody
therapeutics.