Active Site

Cysteine peptidase, asparagine active site (IPR025661)

Short name: Pept_asp_AS


Thiol (cysteine) proteases (EC 3.4.22.-) [PMID: 3148320] are a family of proteolytic enzymes which contain an active site cysteine. Catalysis proceeds through a thioester intermediate and is facilitated by a nearby histidine side chain; an asparagine completes the essential catalytic triad.

Cysteine peptidases have characteristic molecular topologies, which can be seen not only in their three-dimensional structures, but commonly also in the two-dimensional structures. These are peptidases in which the nucleophile is the sulphydryl group of a cysteine residue. Cysteine proteases are divided into clans (proteins which are evolutionary related), and further sub-divided into families, on the basis of the architecture of their catalytic dyad (cysteine-histidene) or triad [PMID: 11517925].

Modification of the catalytic triad, especially of its first amino acid (cysteine), has been postulated as a suitable target for a chemical modulation of enzyme function. This is the case for silicateins, where the cysteine residue has been replaced by a serine [PMID: 17408887]. Silicateins represent a group of enzymes possessing bi-functional activity; in addition to the silica-condensing activity, they possess a proteolytic (cathepsin-like) activity [PMID: 18497895].

The sequences around the three active site residues are well conserved. This entry represents the asparagine active site. The catalytic triad consists of this entry, IPR000169 and IPR025660. This catalytic triad detects mainly proteases of the C1 family, including papain and several cathepsins.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns