Chymopapain: A cysteine endopeptidase isolated from papaya latex. Preferential cleavage at glutamic and aspartic acid residues. EC 18.104.22.168.Intervertebral Disc Chemolysis: The dissolving of the nucleus pulposus, the semi-gelatinous tissue of a displaced INTERVERTEBRAL DISC. It is usually achieved by the direct injection of a proteolytic enzyme, especially CHYMOPAPAIN, into the herniated disc.Ficain: A sulfhydryl proteinase with cysteine at the active site from ficus latex. Preferential cleavage is at tyrosine and phenylalanine residues. EC 22.214.171.124.Bromelains: Protein-digesting and milk-clotting enzymes found in PINEAPPLE fruit juice and stem tissue. Enzymes from the two sources are distinguished as fruit bromelain and stem bromelain. This enzyme was formerly listed as EC 126.96.36.199.Papain: A proteolytic enzyme obtained from Carica papaya. It is also the name used for a purified mixture of papain and CHYMOPAPAIN that is used as a topical enzymatic debriding agent. EC 188.8.131.52.Cystatins: A homologous group of endogenous CYSTEINE PROTEINASE INHIBITORS. The cystatins inhibit most CYSTEINE ENDOPEPTIDASES such as PAPAIN, and other peptidases which have a sulfhydryl group at the active site.2,2'-Dipyridyl: A reagent used for the determination of iron.Intervertebral Disc Displacement: An INTERVERTEBRAL DISC in which the nucleus pulposus has protruded through surrounding fibrocartilage. This occurs most frequently in the lower lumbar region.