(Greek: a suffix indicating an enzyme)
From Greek diastasis and then (diast)ase, separation, interval [from dia-, through, apart, plus stasis, a standing]; an amylase that converts starch to maltose. Added to the name of a substance it usually indicates an enzyme that hydrolyzes that substance; for example, proteinases hydrolyze proteins and asparaginase hydrolyzes asparagine.
This suffix is also described as the termination denoting an enzyme, suffixed to the name of the substance (substrate) upon which the enzyme acts; e.g., phosphatase, lipase, and proteinase. It may also indicate the reaction catalyzed, e.g., decarboxylase and oxidase. Enzymes named before the convention was established generally have an -in ending; e.g., pepsin, ptyalin, and trypsin.