Proteinases are enzymes that catalyse the breakdown of proteins. Proteinases are involved in many biological functions, including the digestion of ingested proteins, the breakdown of old proteins, and cell signalling. They also facilitate the formation of new protein products.

低浓度的Proteinase导致alpha 1I3发生了少量的二聚化，但在纯化的二聚体或单体之间未检测到抑制作用或受体结合的差异。将22和64 kDa的Kininogen与alpha 1I3- 或 alpha 2M-结合的papain反应以探测该Proteinase活性位点的可及性。[1]