Figure 1. Phylogenetic tree of α-amylase proteins from representative taxa of the three domains of life.

Abbreviations used and sources of the α-amylases are defined in Table S1. The tree is based on the alignment made in CLUSTAL W of the partial sequences encoding the (β/α)₈ barrel. Two separate groups of fungal α-amylases, intracellular (circled, GH13_5) and extracellular (GH13_1), are distinctly noted. The branch length is proportional to the sequence divergence. Numbers along branches are bootstrap values (1000 replicates). The scale bar (bottom-left corner) indicates 0.05 amino acid substitutions per site.