Structure-based sequence alignment of mature truncated and complete hyaluronidases. Full-length hyaluronidases from Echis pyramidum leakeyi (E_pyramidum; Genbank: ABI33941.1), Hy-L-1000 truncated hyaluronidase from Echis carinatus sochureki (E_carinatus; Genbank: ABI33950.1), full-length hyaluronidase from Bitis arietans (B_arietans; Genbank: ABI33945.1), Hy-L-1000 truncated hyaluronidase from Bitis arietans (B_arietans; Genbank: ABI33947.1) and human hyaluronidase (Human_hyal; Genbank: 2PE4). Key catalytic residue is shown in red and positional residues appear in blue. Cysteine residues are marked in black. Secondary structures were based on the human hyaluronidase crystal structure. Secondary structure elements for human hyaluronidase are shown below the sequences: pink arrows represent β-strands, blue cylinders α-helices, and red cylinders 310 helices.