Figure 8.

Crystal structures of the TTR ligand complex with 1a and the TTR conjugate resulting from the reaction between TTR and 1. (A) Quaternary structure of the fluorescent conjugate resulting from the reaction between TTR and 1, shown as a ribbon representation with monomers colored individually. (PDB accession code 4L1S) (B) Close up view of the T₄ pocket depicting the substructure of 1 covalently attached to the Lys15 residue via an amide bond. (C) Close up view of the T₄ pocket showing 1a in complex with TTR. (PDB accession code 4L1T). A Connolly molecular surface was applied to residues within 10 Å of ligand in the T₄ binding pocket depicting a hydrophobic surface as gray and a polar surface as purple. HBPs 3 and 3′ are composed of the methyl and methylene groups of S117/117′, T119/119′, and L110/110′. HBPs 2 and 2′ are made up by the side chains of L110/110′, A109/109′, K15/15′, and L17/17′. The outermost HBPs 1 and 1′ are lined by the methyl and methylene groups of K15/15′, A108/108′, and T106/106′.