Figure 1

Alignment of bacterial pepsin homologues with human pepsin A and memapsins 1 and 2. Residues are numbered according to mature human pepsin A. Inserts relative to pepsin A are indicated by letters. Each active site residue (Asp32, Tyr75 and Asp215) is indicated by an asterisk. The hydrophobic-hydrophobic-Gly motifs in the psi-loops are indicated by ampersands. A disulphide bridge is indicated by a slash over one cysteine followed by a number and a backslash preceded by the same number over the second cysteine. The Chroma software [37] has been used to highlight residues according to amino acid properties and to generate the consensus line below each alignment block showing 80% conservation or more. Inserts found in only one sequence have been removed and are indicated by the number of amino acids excised in parentheses.