Papain is a proteolytic enzyme from the cysteine proteinase family. Electrophoretic analysis performed on the refined papain from B.S.C. shows four distinct cysteine proteinases as per their increasing isoelectric points (Ip):
1. Papain "stricto sensu" (Ip: 8.7-8.9),
2. Chymopapain (Ip: 10.4-10.7),
3. Glycyl endopeptidase (Ip: 10.5 - 10.8),
4. Caricain (Ip: > 11.0).

The amino acid sequence of these enzyme components is very similar. More details on these aspects can be obtained by contacting B.S.C.

Papain is extracted from the tropical fruit of the papaya tree. The Carica Papaya grows between the isothermal lines of 77°F (25°C), wherever soil and rainfall are favorable. In these tropical lands the plant has always been popular due to its unique properties. 

One of these properties was the power of its milky juice to soften and dissolve tough meat, to heal sores and ulcers, to clean the skin. The nature of this latex and the enzyme papain was discovered during the colonial period in Congo, where the aboriginals wrapped their elephant meat several days in papaya leaves in order to tenderize it. 

For this purpose, special varieties and climate conditions are required to obtain good quality raw materials. The trees are cultivated on the fertile flanks of mount Ruwenzori in Kivu ( Congo). After ten to twelve months from germination of the plant seeds, the first ripe fruits are produced and the latex can be collected by lightly scoring the skin of the papaya. The latex that drips onto collecting trays is cleaned and dried in typical kilns. 

The dried latex is then crumbled into flakes, put in 50 kg bags and transported to the BSC factories in Belgium.