Pancreas elastase

In addition to the aforementioned allenic steroids, prostaglandins, amino acids and nucleoside analogs, a number of other functionalized allenes have been employed (albeit with limited success) in enzyme inhibition (Scheme 18.56) [154-159]. Thus, the 7-vinylidenecephalosporin 164 and related allenes did not show the expected activity as inhibitors of human leukocyte elastase, but a weak inhibition of porcine pancreas elastase [156], Similarly disappointing were the immunosuppressive activity of the allenic mycophenolic acid derivative 165 [157] and the inhibition of 12-lipoxygenase by the carboxylic acid 166 [158]. In contrast, the carboxyallenyl phosphate 167 turned out to be a potent inhibitor of phosphoenolpyruvate carboxylase and pyruvate kinase [159]. Hydrolysis of this allenic phosphate probably leads to 2-oxobut-3-enoate, which then undergoes an irreversible Michael addition with suitable nucleophilic side chains of the enzyme. 

Some endopeptidases are very specific in cleaving peptide bonds. For example, the Staphylococcus aureus V8 endopeptidase will break only that peptide bond whose carbonyl function has been contributed by glutamic acid (in other words the peptide bond must have a glutamic acid residue lying towards the amino terminal end) bovine pancreas elastase will break only those peptide bonds whose carbonyl function is contributed by alanine, glycine, serine, or valine. 

There are two main classes of proteolytic digestive enzymes (proteases), with different specificities for the amino acids forming the peptide bond to be hydrolyzed. Endopeptidases hydrolyze peptide bonds between specific amino acids throughout the molecule. They are the first enzymes to act, yielding a larger number of smaller fragments, eg, pepsin in the gastric juice and trypsin, chymotrypsin, and elastase secreted into the small intestine by the pancreas. Exopeptidases catalyze the hydrolysis of peptide bonds, one at a time, fi"om the ends of polypeptides. Carboxypeptidases, secreted in the pancreatic juice, release amino acids from rhe free carboxyl terminal, and aminopeptidases, secreted by the intestinal mucosal cells, release amino acids from the amino terminal. Dipeptides, which are not substrates for exopeptidases, are hydrolyzed in the brush border of intestinal mucosal cells by dipeptidases. 

Tincture of the dried seed, on agar plate at a concentration of 30 p,L/disc, was inactive on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Extract of 10 g plant material in 100 mL ethanol was used b Anticoagulation activity. Serpin BSZx (an inhibitor of trypsin and chemotrypsin) inhibited thrombin, plasma kallikrein, factor Vlla/tissue factor, and factor Xa at heparin-independent association rates. Only factor Xa turned a significant fraction of BSZx over as substrate. Activated protein C and leukocyte elastase were slowly inhibited by BSZx, whereas factor Xlla, urokinase and tissue type plasminogen activator, plasmin and pancreas kallikrein, and elastase were not or only weakly affected. Trypsin from Fusarium was not inhibited, while interaction with subtilisin Carlsberg and Novo was rapid, but most BSZx was cleaved as a substrate L... 

Elastase Porcine pancreas AOT/isooctane Solubilization and catalytic studies [80]... 

In the small intestine, proteases released by the pancreas as zymogens become active. Each has a different specificity for the amino acid R-groups adjacent to the susceptible peptide bond. Examples of these enzymes are trypsin, chymotrypsin, elastase, and car-boxypeptidase A and B. The resulting oligopeptides are cleaved by aminopeptidase found on the luminal surface of the intestine. Free amino acids and dipeptides are then absorbed by the intestinal epithelial cells. 

The digestive enzymes trypsin, chymotrypsin, elastase, and proteinase E are related serine proteases. All three are synthesized in the pancreas which secretes 5-10 g per day of proteins, mostly the inactive proenzymes (zymogens) of digestive enzymes.191,192... 

The serine proteases are a large family of proteolytic ( enzymes that use the reaction mechanism for nucleophilic catalysis outlined in equations (3) and (4), with a serine residue as the reactive nucleophile. The best known members of the family are three closely related digestive enzymes trypsin, chymotrypsin, and elastase. These enzymes are synthesized in the mammalian pancreas as inactive precursors termed zymogens. They are secreted into the small intestine, where they are activated by proteolytic cleavage in a manner discussed in chapter 9. 

In chapter 8, we mentioned that the pancreas secretes trypsin, chymotrypsin, and elastase as inactive zymogens, which are activated by extracellular proteases. Trypsin is activated when the intestinal enzyme enter-opeptidase cuts off an N-terminal hexapeptide. Trypsin in turn activates chymotrypsin by cutting it at the N-terminal end between Arg 15 and lie 16. This type of change in the covalent structure of an enzyme is termed partial proteoly-sis. Delaying the activation prevents the digestive enzymes from destroying the pancreatic cells in which they are synthesized. 

The reverse action of a trypsin-free elastase isolated from porcine pancreas was studied in frozen aqueous systems and was found to catalyze peptide bond formation more effectively than in solution at room temperature (Haensler, 1998). The acceptance of free amino acids as nucleophilic amino components indicates a changed specificity of the endoprotease in frozen reaction mixtures. In elastase-catalyzed formation of Ser-, lie-, and Val-X-bonds in frozen aqueous reaction mix-... 

J. D. Wissmann, and H.-D. Jakubke, Reverse catalysis of elastase from porcine pancreas in frozen aqueous systems,... 

Ul. Uhl, W., and Biichler, M., PMN-elastase in comparison with CRP, antiproteases, and LDH as indicators of necrosis in human acute pancreatitis. Pancreas 6, 253 (1991). 

Trypsin, chymotrypsin, and elastase are three of the most important protein-digesting enzymes secreted by the pancreas. Despite their similarities they have different substrate specificity, that is, they cleave different peptide bonds during protein digestion. 

The major group of enzymes produced by the pancreas and secreted into the duodenum as an aqueous bicarbonate solution is the peptidases. There are three endopeptidases, trypsin, chymotrypsin and elastase, and two exopeptidases,... 

For many years a solution of crude acetone powder of bovine or porcine pancreas has been used to disaggregate tissues and to release cultured cells from their substratum. These preparations — referred to as trypsin 1 250 (based on an international standard) — contain not only trypsin but a range of enzymes including chymotrypsin and elastase which are equally important. Purified trypsin seldom is as efficient as the cruder preparations, especially on tissue disaggregation, when mucinous clumps result (Ronaldoni, 1959). 

Elastase Proelastase Pancreas Decapeptide ( ) Trypsin Amino group contributed by small amino acids... 

When the stomach contents pass into the small intestine, the low pH causes the release of the hormone secretin from cells of the small intestine. Secretin causes the release of bicarbonate from the pancreas which neutralizes the hydrochloric acid and allows the hydrolytic enzymes trypsin, chymotrypsin, elastase and carboxypeptidase to function optimally at pH 7-8. 

The pancreas of all mammals so far investigated contain an elastase with similar enzymatic reactions (Lewis et al., 1956 Marrama et al., 1959), but immunological differences have been observed between pancreatic elastases from different species (Moon and Mclvor, 1960). Elastase is secreted in the pancreatic juice as an inactive zymogen, proelastase (Grant and Robbins, 1955 Lamy and Lansing, 1961) which, like other pancreatic enzymes, is activated by trypsin or enterokinase. 

Luminal and Membrane Metabolism of Peptides and Proteins. In meaningful studies on peptide and protein drug absorption in the small intestine, it is prerequisite to distinguish among cavital, membrane contact, and intracellular drug metabolism.Cavital metabolism takes place in the lumen of the small intestine by enzymes such as trypsin, chymotrypsin, carboxypepti-dase, and elastase, which are secreted by the pancreas. Membrane contact metabolism is carried out by aminopeptidases lo-calized on the brush border membrane. Intracellular metabolism occurs inside of the cells. The known intra-celluar enzymes are cytoplasmic peptidases, prolidase, dipeptidase, and tripeptidase.A more detailed dis-cussion of this topic is presented in section Intestinal Absorption Barriers, later. 

The pancreas produces trypsin, chymotrypsin, elastase, and the carboxypeptidases, which act in the lumen of the intestine. 

Total volume of pancreatic juice, amount or concentration of bicarbonate, and activities of pancreatic enzymes are measured in duodenal contents. The enzyme most commonly measured is trypsin, but amylase, lipase, chy-motrypsin, and elastase may also be evaluated. The Lundh test consists of administering a standardized meal consisting of 5% protein, 6% fat, 15% carbohydrate, and 74% nonnutrient fiber. Advantages of the Lundh meal are that it provides a physiological stimulus to the pancreas and is simple to administer. However, administration of the meal prevents determination of the total enzyme and bicarbonate or secretory volume. Moreover, it provides inadequate or no stimu-... 

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