%0 Journal Article %T Accurate prediction of CDR-H3 loop structures of antibodies with deep learning. %A Chen H %A Fan X %A Zhu S %A Pei Y %A Zhang X %A Zhang X %A Liu L %A Qian F %A Tian B %J Elife %V 12 %N 0 %D 2024 Jun 26 %M 38921957 %F 8.713 %R 10.7554/eLife.91512 %X Accurate prediction of the structurally diverse complementarity determining region heavy chain 3 (CDR-H3) loop structure remains a primary and long-standing challenge for antibody modeling. Here, we present the H3-OPT toolkit for predicting the 3D structures of monoclonal antibodies and nanobodies. H3-OPT combines the strengths of AlphaFold2 with a pre-trained protein language model and provides a 2.24 Å average RMSDCα between predicted and experimentally determined CDR-H3 loops, thus outperforming other current computational methods in our non-redundant high-quality dataset. The model was validated by experimentally solving three structures of anti-VEGF nanobodies predicted by H3-OPT. We examined the potential applications of H3-OPT through analyzing antibody surface properties and antibody-antigen interactions. This structural prediction tool can be used to optimize antibody-antigen binding and engineer therapeutic antibodies with biophysical properties for specialized drug administration route.