Biochemical properties and tertiary structure of Scapularisin-3 and Scapularisin-6. (A) Alignment of the primary structure of the defensins: represents Scapularisin-3 and Scapularisin-6. Deduced amino acid sequences of prodefensins are 70 and 74 amino acids for Scapularisin-3 and Scapularisin-6, respectively. After cleavage, both mature proteins contain 38 amino acid residues (mature peptides). Within the α-core motif residues Thr10 and Ser13 in Scapularisin-3 are substituted with Ala10 and Arg13 in Scapularisin-6, enclosed in rectangles, and the six conserved cysteine residues are indicated by stars (♦ , ♦♦ ). (B) Tertiary structure of defensin peptides. Panel B displays the NMR defensin structure from A. gambiae (DEF-AAA; PDB: 2NY8) and the two predicted tertiary structures of Scapularisin-3 (GenBank: EEC13914) and Scapularisin-6 (GenBank: EEC08935). The tertiary structures depict the conserved disulphide bridges (roman numerals), loops, β-sheets, and the α-helix. All structures are coloured from the N-terminus (blue) to the C-terminus (red). Below are the respective electrostatic potentials for each structure in 180° turns (blue = positive; red = negative; white = neutral). (C) The protein backbone alignment in Panel C depicts each structure colour coded as indicated.