Structural alignment of archaemetzincins and metzincins.

<p>(A) Superposition of the three known AmzA structures <i>Af</i>AmzA (yellow), <i>Mk</i>AmzA (green) and <i>Ml</i>AmzA (slate). (B) Close-up view of the Cys₄ zinc finger domains of all three AmzA structures from (A). (D) Superposition of <i>Af</i>AmzA (yellow) with selected metzincins Bap1 (orange), H2-proteinase (grey), acutolysin A (red) and ADAM33 (blue). In place of a Cys₄ zinc finger found in <i>Af</i>AmzA (yellow), the superposed metzincins exhibit two disulfide bonds as shown in (C) using the example of Bap1 (orange). Individual cysteine residues are labeled in accordance with the amino acid sequence of <i>Af</i>AmzA (yellow) in (B) and Bap1 (orange) in (C), respectively. Important secondary structure elements are labeled.