Sequence alignment of T. thermophila extracellular proteases. The identified cysteine proteases in T. thermophila supernatants are compared to papain. The ERFNIN motif is highlighted in red, amino acids that are conserved in all enzymes are green. Amino acids of the catalytic center are marked by *, cysteines that form disulfide bridges by ∅. All peptides found by mass spectrometry in the different proteases are highlighted by either bold, italic, underlined, or doubly underlined letters. Obviously no N-terminal peptides were detected, as only secreted, mature enzymes with cleaved off prepro-peptides (~aa 1-140) were analysed. Peptides around aa 160 are not expected either as the catalytic cysteine that covalently bound to DCG-04 resides at this position.