A Brief Introduction of ProtIdent
Proteases are vitally important to life cycle and have become a main target for drug design. They are generally classified into six types: (1) aspartic, (2) cysteine, (3) glutamic, (4) metallo, (5) serine, and (6) threonine. Different types are responsible for different functions. Therefore, it is important for both basic research and drug development to consider the following problems.

The web server ProtIdent (Protease Identifier) was developed by fusing the functional domain and sequential evolution information. ProtIdent is a 2-layer predictor: the 1st layer is for identifying a query protein as protease or non-protease; if it is a protease, the process will automatically go to the 2nd layer to further identify it among the six functional types.

For a query protein sequence, it will generally take around 25 seconds to get the desired 2-level results with higher than 90% of success expectancy. For very long sequence, it might take a little longer.

For more information, refer to the original paper that has documented the predictor.
Caveat
To obtain the predicted result with the expected success rate, the entire sequence of the query protein rather than its fragment should be used as an input. A sequence with less than 50 amino acid residues is generally regarded as a fragment.