Fig. 2

Complex structure of PDB: 3QXV used to design a synthetic phage-displayed nanobody library. A In the structure of PDB: 3QXV, key amino acids that interact with MTX in the nanobody were analysed. Positions NT, CDR-H1, CDR-H2, CDR-H3, and CDR-H4 are marked in different colours. The SynaGG library was designed using the nanobody based on the PDB: 3QXV structure. Mutated nanobody molecules in the SynaGG library demonstrated a glove-like configuration, which was suitable for panning small molecules. B The red parts in the figure denote the positions of NT, CDR-H1, CDR-H2, CDR-H3, and CDR-H4, including mutation points in the nanobody SynaGG library. The IMGT numbers represent the unique IMGT numbering, denoting the positions of the amino acids. NT-loop represents the nanobody N-terminus position, and X represents the NNK mutation