FIG 6.
Structural analysis of L349F, P399A, and F471C. A and B, L349 is located in the loop in front of the strands of β-sheet B (PDB: 5DU3 and 2OAY).7,31 The substitution of aromatic amino acid F to L349 may cause side-chain clashes with the W299, which could further alter the conformation of S3A and affect the RCL insertion. The P399 is located in a tight turn connecting to the center shutter S6A. The alternation of P to A will disrupt the loop formation and further affect the orientation of R400. C, Structural analysis of F471C. F471 is located at the end of the RCL (PDB: 5DU3).7 It is a highly conserved residue in serpins.32 F is a hydrophobic aromatic amino acid in the protein hydrophobic core. C belongs to the group of polar amino acids. It often resides at the surface of proteins. The introduction of a polar side chain from F471C disrupts the RCL insertion.33 PDB, Protein Data Bank.