Pancreas enzymes

The administration of medium-chain triglycerides has a positive influence on the malabsorption of fat when accompanied by an adequate intake of proteins. Pancreas enzymes may be helpful. Simvastatin or bezafi-brate can be successfully used in the treatment of hyper-cholesterinaemia. (154, 155, 172, 245) The deficiency of... 

A periodic measurement of stool fat excretion by means of the method of Van de Kamec [97] or using the less unpleasant near-infrared analysis [98-100] allows quantitative evaluation of the degree of steatorrhea. Besides this, several function tests where the pancreas is directly stimulated by an infusion of secretin and/or cholecystokinin (reviewed in Ref. 101) or indirect tests requiring the administration of an exogenous pancreas enzyme substrate as V-benzoyl-L-tyrosyl-p-aminobenzoic acid (NBT-PABA) or fluorescein dilaurate (pancreo-lauryl test) (Fig. 12) are available. The NBT-PABA test measures intraluminal... 

Fig. 2. Homologous proteins. Conformation of the polypeptide chains of the two homologous pancreas enzymes, a-chymotrypsin (above) and elastase (below).

Besides ribonuclease from the pancreas, enzymes from a mold are known to spht specifically at certain purine bases (Egami). This is important for the sequence analysis of nucleic acids. 

Diastase or amylase is formed when malt is produced by the germination of barley grains. Malt is therefore a good source of the enzyme. Diastase is also secreted by the salivary glands (when it is known as ptyalin), and also by the pancreas. Its function is to hydrolysef starch to a mixture of maltose and dextrin ... 

The so-called "trypsin," obtainable from pancreatic juice and from fresh extracts of the pancreas, is not a simple enzyme but a mixture of trypsin proper (which hydrolyses proteins to proteoses and peptones) and a series of enzymes which hydrolyse these breakdown products to their constituent amino-acids. The term trypsin," when used below, refers to this mixture. 

ENZYMATIC ANALYSIS WITH CARBOXYPEPTIDASES. Carboxypeptidases are enzymes that cleave amino acid residues from the C-termini of polypeptides in a successive fashion. Four carboxypeptidases are in general use A, B, C, and Y. Carboxypeptidase A (from bovine pancreas) works well in hydrolyzing the C-terminal peptide bond of all residues except proline, arginine, and lysine. The analogous enzyme from hog pancreas, carboxypeptidase B, is effective only when Arg or Lys are the C-terminal residues. Thus, a mixture of carboxypeptidases A and B liberates any C-terminal amino acid except proline. Carboxypeptidase C from citrus leaves and carboxypeptidase Y from yeast act on any C-terminal residue. Because the nature of the amino acid residue at the end often determines the rate at which it is cleaved and because these enzymes remove residues successively, care must be taken in interpreting results. Carboxypeptidase Y cleavage has been adapted to an automated protocol analogous to that used in Edman sequenators. 

The enzymes pancreatin and pancrelipase, which are manufactured and secreted by the pancreas, are responsible for the breakdown of fats, starches, and proteins. These enzymes are necessary for the breakdown and digestion of food. Both enzymes are available as oral supplements. 

These drug are prescribed as replacement therapy for those with pancreatic enzyme insufficiency. Conditions or diseases that may cause a decrease in or absence of pancreatic digestive enzymes include cystic fibrosis, chronic pancreatitis, cancer of the pancreas,... 

For the kinetic resolution of racemic a-acetoxyamide 6 several native enzymes were used (Scheme 5.5). The native Upases from Pseudomonas cepacia (PCL) and porcine pancreas (PPL) showed the highesL although stiU unsatisfactory, enantios-electivity ( = 5.1 and 3.5, respectively). Upon immobilization into a solgel matrix, the enantioselectivity of PCL was improved significantly to 30.5. The covalent immobilization on Eupergit increased the enantioselectivity even more (34.0) [23]. 

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. 

Amylase enters the blood largely via the lymphatics. An increase in hydrostatic pressure in the pancreatic ducts leads to a fairly prompt rise in the amylase concentration of the blood. Neither an increase in volume flow of pancreatic juice nor stimulation of pancreatic enzyme production will cause an increase in senm enzyme concentration. Elevation of intraductal pressure is the important determinant. Stimulation of flow in the face of obstruction can, however, augment the entry of amylase into the blood, as can disruption of acinar cells and ducts. A functional pancreas must be present for the serum amylase to rise. Serum amylase determination is indicated in acute pancreatitis in patients with acute abdominal pain where the clinical findings are not typical of other diseases such as appendicitis, cholecystitis, peptic ulcer, vascular disease or intestinal obstruction. In acute pancreatitis, the serum amylase starts to rise within a few hours simultaneously with the onset of symptoms and remains elevated for 2 to 3 days after which it returns to normal. The peak level is reached within 24 hours. Absence of increase in serum amylase in first 24 hours after the onset of symptoms is evidence against a diagnosis of acute pancreatitis (76). 

A solution to the problem of introns is to isolate mRNA extracted from the human pancreas cells that make insulin. These cells are rich in insulin mRNA from which introns have already been spliced out. Using the enzyme reverse transcriptase it is possible to convert this spliced mRNA into a DNA copy. This copy DNA (cDNA), which carries the uninterrupted genetic information for insulin can be cloned. Although yeast cells (Saccharomyces) can splice out introns it is normal practice to eliminate them anyway by cDNA cloning. 

The complex polymers in feedstuffs are broken down to the constituent building blocks by a sequential process. Hydrolysis of the polymers is initiated in the lumen of the GIT by enzymes and other secretions produced by the pancreas, stomach, intestine, liver and gall bladder, and other GIT tissues, and completed by another suite of enzymes associated with the brush border membrane (BBM) or intracellular organelles. Anti-nutrient phytochemicals can decrease the hydrolysis of feedstuffs, and thereby reduce nutrient availability, either by increasing the inherent resistance of the polymers to hydrolysis or by decreasing the activities or amounts of enzymes and other secretions produced by the GIT. 

Pancreatic secretion for many, if not most, species is regulated in order to insure adequate protein digestion. Correspondingly, protease inhibitors have a greater impact on pancreatic secretion than do inhibitors of amylase and lipase (Toskes, 1986). The secretory response of the exocrine pancreas to protease inhibitors can be rapid (< 10 min), does not involve parallel increases in the secretion of all enzymes (Holm et al., 1992), and is probably mediated by a signaling pathway (see below). 

Another approach to the synthesis of chiral non-racemic hydroxyalkyl sulfones used enzyme-catalysed kinetic resolution of racemic substrates. In the first attempt. Porcine pancreas lipase was applied to acylate racemic (3, y and 8-hydroxyalkyl sulfones using trichloroethyl butyrate. Although both enantiomers of the products could be obtained, their enantiomeric excesses were only low to moderate. Recently, we have found that a stereoselective acetylation of racemic p-hydroxyalkyl sulfones can be successfully carried out using several lipases, among which CAL-B and lipase PS (AMANO) proved most efficient. Moreover, application of a dynamic kinetic resolution procedure, in which lipase-promoted kinetic resolution was combined with a concomitant ruthenium-catalysed racem-ization of the substrates, gave the corresponding p-acetoxyalkyl sulfones 8 in yields... 

This gene is broadly distributed in skeletal muscle, heart, uterus, and in a variety of non-muscle cells. The mRNA levels are particularly high in intestine, lung and spleen, whereas they are very low in liver, testes, kidney and pancreas. In the muscle tissue SERCA3 may be confined primarily to non-muscle cells (vascular smooth muscle, endothelial cells, etc.). The C-terminus of SERCA3 is Asp-Gly-Lys Lys-Asp-Leu-Lys (Table I) it may serve as a sorting signal for retention of the enzyme in the endoplasmic reticulum [57]. 

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