BTD-7 has antimicrobial activity against the Gram-negative bacterium E.coli ML35, the Gram-positive bacterium S.aureus 502a, and the fungus C.albicans 16820. BTD-7 is a cyclic heterodimer composed of subunits A and D; disulfide-linked. Forms a cyclic peptide with subunit A (BTD-7). An additional intersubunit disulfide bond is formed. BTD-7, heterodimer, cyclized. Belongs to the alpha-defensin family. Theta subfamily.