Trypsin, activity during pancreas

Some of the serine proteases are stored in the pancreas as inactive precursors that may be activated by proteolysis. Trypsinogen, for example, is converted to trypsin by the removal of the N-terminal hexapeptide on the cleavage of the bond between Lys-6 and Ile-7 by enterokinase. Chymotrypsinogen is activated by the tryptic cleavage of the bond between Arg-15 and He-16. (In this case, further proteolysis by the chymotrypsin that is released during the activation leads to the different forms of the enzyme—Figure 16.5.)... 

Trypsin is typically considered an enzyme found in the pancreas and small intestine. However, trypsin, thrombin, and plasmin are also widely expressed in endothelium, including epithelial immune cells as well as neurons. Upregulated expression and release occurs during both acute and chronic inflammation [60], Autocrine release of trypsin and thrombin causes activation of protease-activated receptors (PARs) reaction leading to cellular proliferation and inflammation [4], This response includes release of proteins by all cells during chronic inflammation. Bik prevents PAR activation on cell surfaces. 

Dietary triglycerides are hydrolyzed in the small intestine by pancreatic lipase. This enzyme action is associated with a cofactor, colipase, also a pancreatic protein, molecular weight (MW) 12,000, which helps to anchor lipase to the fat droplets. Without colipase, lipase is rapidly denatured. Colipase is apparently secreted by the pancreas as a zymogen and is activated to its active form in the small intestine by trypsin. Pancreatic lipase appears in the circulation in large amounts during acute pancreatitis. 

The term catalysis was applied to the biological phenomena listed above and to several other reactions discovered in the next several years. The active component of bitter almonds was named emulsin in 1837. Other carbohydrate-splitting activities (ptyalin in saliva, amylase in malt) had already been described. Pepsin and trypsin, protein-digesting agents from the stomach and pancreas, were also discovered during this period. The activities of these materials were contrasted with the materials responsible for fermentation. Early theories of Willis and of Stahl to explain fermentation as a disruption caused by violent motion of... 

Followed by these observations, Bassindale et al. [ 19,20] studied the use of various homologous lipase and protease enzymes to catalyze the formation of molecules with a single siloxane bond during the in vitro hydrolysis and condensation of alkoxysilanes under mild reaction conditions. They found that non-specific interactions with trypsin promoted the hydrolysis of alkoxysilanes, while the active site was determined to selectively catalyze the condensation of silan-ols. One interesting observation was that when trypsin from various sources was employed different extents of conversion were observed. Comparatively, the activity of trypsin from a bovine pancreas was greater than the alternate sources of trypsin. Although various sources (e.g., mammalian, fish) of trypsin are similar (e.g., tertiary structure), their selectivity and activity was found to be different due to different optimum pH ranges and/or levels of calcium (an additive). 

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