Figure 2

Structure-based alignment of the homologous structures of SDRs. Secondary structural elements are presented above the sequence. The β-strands (β1–7) and α-helices (α1–8) are numbered from the N terminus. TT, β-turns; η (η1, η2), 310 helix. The conserved catalytic tetrad residues are indicated as green circles. (B) Close-up view of the superimposed conserved catalytic tetrad. The tetrad residues in SmSDR are drawn as thick stick model.