Cellular Trypsin

KC Cheah, LE Leong, AG Porter. Site-directed mutagenesis suggests close functional relationship between a human rhinovirus 3C cysteine protease and cellular trypsin-like serine proteases. J Biol Chem 265 7180-7187, 1990. 

The serine proteases are the most extensively studied class of enzymes. These enzymes are characterized by the presence of a unique serine amino acid. Two major evolutionary families are presented in this class. The bacterial protease subtilisin and the trypsin family, which includes the enzymes trypsin, chymotrypsin, elastase as well as thrombin, plasmin, and others involved in a diverse range of cellular functions including digestion, blood clotting, hormone production, and complement activation. The trypsin family catalyzes the reaction ... 

A number of proteomic studies on archival material have utilized Liquid Tissue (Expression Pathology, Inc., Gaithersburg, MD), a commercial protein extraction kit for FFPE tissue.4,9,25-28 This kit is also based upon HIAR techniques and shares a similar work flow to the methods already discussed. Thin, typically 5-10pM, sections are cut from paraffin tissue blocks, the paraffin is removed, and the tissue deparaffinized and rehydrated in alcohols and distilled water before microdissection. The cellular material is then suspended in Liquid Tissue buffer and heated at 95°C for 90 min. Trypsin is added, and the material is digested overnight at 37°C prior to reduction with DTT and analysis by LC-MS/MS.26... 

Vertebrates contain several proteins that maintain the integrity of the blood plasma circulatory system. These contain domains that are specific to vertebrates (Gla, FN1, FN2) (Patthy, 1985), domains that are found in different contexts in invertebrates and/or protists (FBG, APPLE, KR) (Xu and Doolittle, 1990 Eschenbacher et al., 1993 Wilson et al., 1993) and a domain that is found in all cellular life (trypsin-like serine protease, Tryp SPc). The invertebrate versions of these domains, however, are found in molecular contexts that differ considerably from their vertebrate extracellular counterparts, indicating that although these nonenzy-... 

The classical pathway may be activated immunologically by antigen-antibody complexes and aggregated immunoglobulins, and non-immunologically by a number of chemically diverse substances, including DNA, C-reactive protein. Staphylococcal protein A, trypsin-like enzymes and certain cellular membranes (Table III). 

Ricin is a potent cellular protein toxin contained in the beans of the castor been plant (Ricinus communis), which is extensively cultivated for oil production and is also a common ornamental garden plant. Ricin is able to inhibit ribosomal protein synthesis eventually causing cell death, and owing to these properties it has been allegedly used in terrorist and criminal activities. After trypsin digestion of castor bean crude extracts, Ostin et al. [105] were able to unambiguously... 

Studies on cellular surfaces. Trypsin leads to loss of surface proteins including glycoproteins and other antigens and it is these changes which presumably lead to cell death when trypsinisation is prolonged. 

There is some evidence that some larvae of some species (e.g. T. pisiformis) can release substances which inhibit proteolytic enzymes such as trypsin and chymotrypsin (591) (see Chapter 4). Other host cellular activities reported to be modified by parasite secretions are cell differentiation, macrophage activation, responsiveness to mitogens, cytotoxicity and complement activation (687). 

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. 

Olear T, Nouza K. Thrombin and trypsin receptors The same mechanism of signaling on cellular surfaces. Bratisl Lek Listy 1999 100 75-79. 

In the absence of any specific information about the nature of such activities, it is often best to mix a cocktail containing several or all of the available proteolytic inhibitors. These include such compounds as 1,10-phenanthroline, soybean trypsin inhibitor, leupeptin, benzamidine, antipain, aprotinin, phenyl-methanesulfanyl fluoride, and diisopropylfluorophosphate. As a precaution against any enzyme destruction, such a cocktail is best added to the buffer in which the cellular lysis will be carried out (Fig. 5.6). 

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