Figure 5

Structural homology modeling of AaLT and AaSPVI using the Protein Model Portal (PMP) developed by the Swiss Institute of Bioinformatics. A) Structure of the heel fly collagenase (PDB 1hyl) and AaLT model, which was generated by PMP using the heel fly collagenase structure as a scaffold. The heel fly collagenase and AaLT proteins are 40% identical at the amino acid level. Amino acid residues in the catalytic triad in the heel fly collagenase (His57, D102, S195) and AaLT model (His69, D116, S209) are shown in red CPK, along with the discerning serine residue at the bottom of the specificity pocket, which is shown in magenta CPK. Three distinct amino acids located near the extended substrate-binding site in AaLT and AaSPVI are shown in stick style and labeled. B) Structural model of AaSPVI generated by PMP using the salmon cation trypsin structure (PDB 1mbq) as the scaffold. The AaSPVI and salmon proteins are 44% identical at the amino acid level. The catalytic triad residues are shown in red CPK (His81, D125, S221), and the discerning aspartate in the specificity pocket is colored salmon CPK. C) Structural alignment of the AaLT and AaSPVI models shown in the same ribbon colors as in A and B. The S203 (AaLT) and D215 (AaSPVI) residues in the specificity pockets are shown in CPK. The structural alignment was rendered using ICM BrowserPro (Molsoft).