Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proteolytic digestion of GPIIIa on intact platelets by chymotrypsin, thrombin, plasmin, trypsin, and staphylococcal V8 protease was monitored in immunoblot studies employing three different antibodies to GPIIIa, one of which was made against a 13-residue synthetic peptide containing the amino terminus of GPIIIa. Chymotrypsin, plasmin, and trypsin gave similar patterns, from which it could be inferred that the major products after extensive digestion were two-chain molecules composed of amino-terminal fragments of Mr approximately 17,000-18,000 disulfide bonded to carboxyl-terminal remnants of Mr approximately 58,000-70,000. These patterns suggest that GPIIIa contains a large disulfide-bonded loop of at least 325 amino acids that is susceptible to proteolytic cleavage, and that the 4 cysteine residues between residues 177 and 273 bond with each other. Such a structure can also account for the presence of the PIA1 epitope, which has recently been localized to a polymorphism at position 33 on these late digestion products. Thrombin did not proteolyze GPIIIa even at 2.5 units/ml. Still to be resolved is whether the minor immunoreactive GPIIIa bands found on normal platelets are related to in vivo or in vitro proteolysis and whether GPIIIa proteolysis plays a role in chymotrypsin-induced exposure of the GPIIb/IIIa receptor.
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PMID:Evidence that platelet glycoprotein IIIa has a large disulfide-bonded loop that is susceptible to proteolytic cleavage. 252 61

Effective treatment of malabsorption due to severe pancreatic exocrine insufficiency requires delivery of sufficient enzymatic activity into the duodenal lumen simultaneously with meal nutrients. To achieve this, modern therapeutic concepts recommend administration of 25,000 to 40,000 units of lipase per meal using pH-sensitive pancreatin microspheres. In case of treatment failure, dosage should be increased two to three times. If this still is not successful, compliance may be checked by measurement of fecal chymotrypsin, although this is not a standardized procedure. In the compliant patient, diagnosis of pancreatic exocrine insufficiency needs to be reviewed, particularly cases of celiac disease, (concomitant) bacterial overgrowth, and blind loop syndrome, as well as giardiasis, which need to be excluded or otherwise be treated specifically. Finally, additional acid suppression with application of unprotected pancreatin and/or reduced fat intake may help to control malabsorption. Still, in most patients, lipid digestion cannot be completely normalized by current standard therapy. On the one hand, this leads to loss of energy that may only partly be compensated for by increased nutrient intake. On the other hand, increased nutrient exposition of distal intestinal sites may release excessive amounts of mostly inhibitory distal intestinal neurohumoral mediators, and thereby disturb gastrointestinal secretory and motor functions. Consequently, future developments are needed for optimizing treatment.
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PMID:Pancreatic Enzyme Supplementation Therapy. 1295 43