Figure 2. (A) Phylogenetic tree showing evolutionary relationship of 40 CHAPK homologs (15 from PDB BLAST and 25 from nr BLAST databases). The maximum parsimony tree was obtained using the Close-Neighbor-Interchange algorithm level 3 in MEGA4 with a bootstrap consensus setting of 1,000 replicates. CHAPK and the 2K3A CHAP protein are underlined. (B) Expresso alignment of CHAPK target sequence and 2K3A structural template sequence. Highly-conserved cysteine (C), histidine (H) and glutamic acid (E) active site residues present in both proteins have been identified and are shown in black boxes.