Analysis of Cu, Zn Superoxide dismutase (SOD) protein family. Multiple sequence alignment (CLUSTALX) of protein sequences identified in a cDNA library of unfed/2 d fed or 6 d fed Dermacentor variabilis midguts (DvM), Argas monolakensis (Am) and Ixodes scapularis (Is) Cu, Zu SOD. Arrowhead indicates the position of residues that bind either copper (C) or zinc (Z) and the residues that form the disulfide bridges (S-S). Shadding respresents 100% identity (black) or similarity (grey). Alignments were conducted using CLUSTALX.