Trypsin http://en.wikipedia.org/wiki/Trypsin Function
In the duodenum, trypsin catalyzes the hydrolysis of peptide bonds, breaking down proteins into smaller peptides. The peptide products are then further hydrolyzed into amino acids via other proteases, rendering them available for absorption into the blood stream. Tryptic digestion is a necessary step in protein absorption as proteins are generally too large to be absorbed through the lining of the small intestine.
Trypsin is produced in the pancreas, in the form of the inactive zymogen trypsinogen. When the pancreas is stimulated by cholecystokinin, it is then secreted into the first part of the small intestine (the duodenum) via the pancreatic duct. Once in the small intestine, the enzyme enteropeptidaseactivates it into trypsin by proteolytic cleavage. Auto catalysis can happen with trypsin with trypsinogen as the substrate.. This activation mechanism is common for most serine proteases, and serves to prevent autodegradation of the pancreas.
Mechanism
The enzymatic mechanism is similar to that of other serine proteases. These enzymes contain a catalytic triad consisting of histidine-57, aspartate-102, and serine-195.[4] These three residues form a charge relay that serves to make the active site serine nucleophilic. This is achieved by modifying the electrostatic environment of the serine. The enzymatic reaction that trypsins catalyze is thermodynamically favorable but requires significantactivation energy (it is "kinetically unfavorable"). In addition, trypsin contains an "oxyanion hole" formed by the backbone amide hydrogen atoms of Gly-193 and Ser-195, which serves to stabilize the developing negative charge on the carbonyl oxygen atom of the cleaved amides.
The aspartate residue (Asp 189) located in the catalytic pocket (S1) of trypsins is responsible for attracting and stabilizing positively charged lysineand/or arginine, and is, thus, responsible for the specificity of the enzyme. This means that trypsin predominantly cleaves proteins at the carboxylside (or "C-terminal side") of the amino acids lysine and arginine except when either is bound to a C-terminal proline.[5], although large-scale mass spectrometry data suggest cleavage occurs even with proline. [6] Trypsins are considered endopeptidases, i.e., the cleavage occurs within thepolypeptide chain rather than at the terminal amino acids located at the ends of polypeptides.
Properties
Trypsins has an optimal operating pH of about 7.5-8.5 and optimal operating temperature of about 37°C.[5]
The activity of trypsins is not affected by the inhibitor tosyl phenylalanyl chloromethyl ketone, TPCK, which deactivates chymotrypsin. This is important because, in some applications, like mass spectrometry, the specificity of cleavage is important.
Trypsins should be stored at very cold temperatures (between −20°C and −80°C) to prevent autolysis, which may also be impeded by storage of trypsins at pH 3 or by using trypsin modified byreductive methylation. When the pH is adjusted back to pH 8, activity returns.

The Effect of Temperature on the Protease Enzyme Trypsin http://www.123helpme.com/view.asp?id=122018

Trypsin is an enzyme, enzymes exist in all living things. They are composed of polymers of amino acids and are produced in living cells.
Each cell contains several hundred enzymes. Their job is to catalyse chemical reactions. In the digestive process, Trypsin breaks down protein molecules into amino acids. Enzymes are known as "biological catalysts" as they increase the rate at which reactions occur within living organisms, it is not possible for enzymes to die or become used up, however, they can be denatured which stops them from functioning correctly. They can be denatured or affected by temperature, pH and concentration of the enzyme, this is why homeostasis, the keeping of certain bodily functions including pH and temperature constant is so important. Temperature