Classification of Enzymes
It has been a long tradition of giving enzymes names ending in 'ase'. The only major exception to this 'ase' is the proteolytic enzymes, whose names usually end with '-in', e.g. trypsin. In the background of lack of consistency in the nomenclature, it becomes apparent as the list of known enzymes rapidly grew, that there was a need for a systematic way of naming and classifying enzymes.