<P> Protease containing plant - solutions called vegetarian rennet has been in use for hundreds of years in Europe and middle - east for making kosher and halal Cheeses . Vegetarian rennet from Withania coagulans has been in use for thousands of years as Ayurvedic remedy for digestion and diabetes in the Indian subcontinent . It is also used to make Paneer . </P> <P> Plant genomes encode hundreds of proteases, largely of unknown function . Those with known function are largely involved in developmental regulation . Plant proteases also play a role in regulation of photosynthesis . </P> <P> Proteases are used throughout an organism for various metabolic processes . Acid proteases secreted into the stomach (such as pepsin) and serine proteases present in duodenum (trypsin and chymotrypsin) enable us to digest the protein in food . Proteases present in blood serum (thrombin, plasmin, Hageman factor, etc .) play important role in blood - clotting, as well as lysis of the clots, and the correct action of the immune system . Other proteases are present in leukocytes (elastase, cathepsin G) and play several different roles in metabolic control . Some snake venoms are also proteases, such as pit viper haemotoxin and interfere with the victim's blood clotting cascade . Proteases determine the lifetime of other proteins playing important physiological role like hormones, antibodies, or other enzymes . This is one of the fastest "switching on" and "switching off" regulatory mechanisms in the physiology of an organism . </P> <P> By complex cooperative action the proteases may proceed as cascade reactions, which result in rapid and efficient amplification of an organism's response to a physiological signal . </P>

Based on the residues in the active site what family of proteases does pepsin belong to