Proteolytic enzymes table

Mammals, fungi, and higher plants produce a family of proteolytic enzymes known as aspartic proteases. These enzymes are active at acidic (or sometimes neutral) pH, and each possesses two aspartic acid residues at the active site. Aspartic proteases carry out a variety of functions (Table 16.3), including digestion pepsin and ehymosin), lysosomal protein degradation eathepsin D and E), and regulation of blood pressure renin is an aspartic protease involved in the production of an otensin, a hormone that stimulates smooth muscle contraction and reduces excretion of salts and fluid). The aspartic proteases display a variety of substrate specificities, but normally they are most active in the cleavage of peptide bonds between two hydrophobic amino acid residues. The preferred substrates of pepsin, for example, contain aromatic residues on both sides of the peptide bond to be cleaved. 

Homogenates of MetruUum senile, possibly the world s most common large sea anemone, yield extracts that are powerfully hemolytic for washed mammalian erythrocytes (22). The active substance, metridiolysin, is a protein of molecular weight approximately 80,000. In contrast to the sphingomyelin-inhibitable toxins, metridiolysin is an acidic protein having a pi of about 5. It is thermolabile and is inactivat by proteolytic enzymes. The optimal pH for hemolysis is between 5 and 6, and at pH 8 the lysin is inactive. It can be dissociated into two subunits of unequal size. Besides being cytolytic in vitro, metridiolysin is lethal when injected intravenously into mice. As shown in Table IV erythrocytes from the horse or dog are about a hundred times as sensitive to lysis as those from the mouse, and erythrocytes from other animals tested are intermediate in sensitivity. 

Thus, more than 500 peptidases are listed in the Handbook of Proteolytic Enzymes [7a], this classification being summarized in part in Table 2.1. 

Prostate Citric acid Acid phosphatase Spermidine Zinc ions Calcium ions Proteolytic enzymes Oxidation generates ATP and removes protons (Chapter 6) Hydrolyses phosphatidylcholine Not known Helps to stabilise structure of DNA (see Table 15.4) Stimulate coagulatiou of semeu in vagina Gradual breakdowu of coagulum to release sperm... 

Members of both structural families of serine proteinases, the trypsinlike and the subtilisin-like, have been found to bind Ca " (references in Tables 1 and II). The role of Ca " in all of these proteolytic enzymes appears to be one of stabilization of structure and/or maintenance of... 

Polymers may also inhibit proteolytic enzymes or be used to augment the activity of proteolytic inhibitors (Table 11.6). The administration of small molecule protease inhibitors in conjunction with the peptide, however, has been examined with some success (Fujii et al. 1985) however, the ability of these molecules to protect the protein has been hampered by the fact that they tend to cause systemic side effects (Yagi et al. 1980 McCaffrey and Jamieson 1993 Plumpton et al. 1994). Many protease inhibitors have been specific for the proteases in the stomach and intestine, but some of these factors are not specific and some control over absorption of the... 

More extensive studies were carried out on polymeric materials modified with a hydrogel containing covalently immobilized heparin and trypsin 136,137>. Table 18 compiles the results of in vitro tests of the thus-modified low-density polyethylene. Obviously, co-immobilization of heparin and proteolytic enzyme onto polyethylene results in an increase of the blood clotting time and decreases the number on adhered platelets as compared to immobilization of heparin alone. 

The role of zinc in the enzymes listed in Table 12 is very often that of a strong Lewis acid, in which substrates are coordinated, polarized and hence activated. In other cases, zinc may play a regulatory, structural or template role. Zinc may also have a structural function in other biological molecules, for example in the unwinding and subsequent rewinding of the double-stranded polymers involved in replication and transcriptional processes. There is also evidence for a role for zinc in the stabilization of membranes and cell walls.463 The high concentrations of zinc in certain snake venoms reflect the presence in the venom of proteolytic enzymes and hemorrhagic toxins that all require zinc for activity.464... 

Papain is a mixture of proteolytic enzymes found in extract of papaya, the fruit of the papaya tree (Carica papaya). It is taken orally in the belief that it reduces edema, inflammation, herpes zoster symptoms, diarrhea, and psoriasis symptoms. The pharmacological mechanisms by which papain may affect coagulation are not known. Patients receiving warfarin should be advised to avoid papain supplementation until further information about this potential interaction becomes available (Table 4.4). 

Table IV. Hydrolysis of the Isodipeptide [14C-methyl]-c-N -L-Methionyl-L-lysine by the Proteolytic Enzymes of the Alimentary Tract...

Some examples relating the importance of proteolytic enzymes to the quality, quality assessment, and processing of fish, fishery wastes, and other marine products are summarized in Tables I and II. 

Table I. Relevance of Proteolytic Enzymes to the Quality of Seafood...

Table II. Proteolytic Enzymes as Food-Processing Aids...

Table 1. Proteolytic enzymes and typical incubation conditions.

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