Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of gastric emptying of nutrients on plasma cholecystokinin and pancreatobiliary functions is poorly understood. We therefore temporally related the emptying of fat, protein, and glucose of a mixed meal to release of the gut hormones cholecystokinin, pancreatic polypeptide, and peptide YY and outputs of trypsin, lipase, bilirubin, and bile salts. Five healthy volunteers with a multilumen duodenal tube ingested a mixed meal with phase-specific markers for the aqueous phase, liquid fat, solid fat, and solid protein phases. Duodenal passage was determined by intraduodenal infusion of a second set of phase-specific nonabsorbable markers. Plasma cholecystokinin levels and pancreatobiliary secretions rose to a maximum at 30-60 min and then gradually declined (p less than 0.01) despite continued entry of protein and fat into the duodenum throughout the whole 4-h experimental period. High levels of both pancreatic polypeptide and peptide YY were observed in the last 2 h of the experiment. Release of factors capable of inhibiting cholecystokinin release and subsequently pancreatobiliary secretion may be responsible for the observed time-course.
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PMID:Temporal relationships of cholecystokinin release, pancreatobiliary secretion, and gastric emptying of a mixed meal. 316 98

Thyroxine modulates the ontogenic changes of animal tissues. In this study, the effects of experimental hyperthyroidism on the adult rat pancreas, small intestine, and serum gastrin were evaluated. Hyperthyroidism was induced by oral feeding of thyroxine (T4) in increasing dosages (150-450 micrograms/kg body weight; 3 weeks) and controlled by measurements of the circulating hormones. The increase of thyroid hormones in blood (T4 ng/dl: thyroxine-treated rats 10.8 vs. controls 3.3; p less than 0.01; given are means) was accompanied by hypergastrinemia (IR-gastrin pg/ml: T4-treated rats 169 vs. controls 25; p less than 0.05). The T4-treated animals consumed more food but lost about 20 g of their initial body weight. Pancreatic wet weight (g: T4-treatment 1.72 vs. controls 1.42; p less than 0.05), DNA (micrograms/g body weight: T4-treatment 2.42 vs. controls 1.5; p less than 0.05), and protein (micrograms/g body weight: T4-treatment 131.7 vs. controls 63.5; p less than 0.05) were increased, whereas no pronounced influence on pancreatic amylase, trypsin, and chymotrypsin was found. The gut wet weight after thyroxine administration (18.1 g vs. 15.4 g of controls; p less than 0.05) was elevated, but length, DNA, protein, and brush border enzyme activities remained unaltered. Our data demonstrate in adult rats a small but significant trophic response of pancreas and gut to repeated oral thyroxine administration.
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PMID:Influence of experimental hyperthyroidism on the adult rat pancreas, small intestine, and blood gastrin levels. 320 18

An insecticidal protein gene from Bacillus thuringiensis var. aizawai was cloned in Escherichia coli. The cloned gene expressed at a high level and the synthesized protein appeared as an insoluble, phase-bright inclusion in the cytoplasm. These inclusions were isolated by density gradient centrifugation, the isolated protein was activated in vitro by different proteolytic regimes and the toxicity of the resulting preparations was studied using insect cells grown in tissue culture. The inclusions consisted of a 130 kDa polypeptide which was processed to a protease-resistant 55 kDa protein by tryptic digestion. This preparation lysed lepidopteran (Choristoneura fumiferana) CF1 cells but not dipteran (Aedes albopictus) cells. When the crystal protein was activated by sequential treatment, first with trypsin and then with Aedes aegypti gut proteases, the resulting 53 kDa polypeptide was now toxic only to the dipteran cells and not to the lepidopteran cells. Thus the dual specificity of this var. aizawai toxin results from differential proteolytic processing of a single protoxin. The trypsin-activated preparation was weakly active against Spodoptera frugiperda cells. Membrane binding studies of the trypsin-activated toxin revealed a 68 kDa protein in the lepidopteran cell membranes, which may be the receptor for this toxin.
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PMID:Characterization of the toxicity and cytopathic specificity of a cloned Bacillus thuringiensis crystal protein using insect cell culture. 333 Jul 56

Uptake of [3H]oleate by canine or rat cardiac myocytes is saturable, displays the countertransport phenomenon, and is inhibited by phloretin and trypsin. Cardiac myocytes contain a basic (pI approximately 9.1) 40-kD plasma membrane fatty acid binding protein (FABPPM) analogous to those recently isolated from liver, adipose tissue, and gut, unrelated to the 12-14-kD cytosolic FABP in these same tissues. An antibody to rat liver FABPPM selectively inhibits specific uptake of [3H]oleate by rat heart myocytes at 37 degrees C, but has no influence on nonspecific [3H]oleate uptake at 4 degrees C or on specific uptake of [3H]glucose. Uptake of long-chain free fatty acids by cardiac muscle cells, liver, and adipose tissue and absorption by gut epithelial cells is a facilitated process mediated by identical or closely related plasma membrane FABPs.
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PMID:Oleate uptake by cardiac myocytes is carrier mediated and involves a 40-kD plasma membrane fatty acid binding protein similar to that in liver, adipose tissue, and gut. 341 74

The processing of preprocholecystokinin in human pituitary extracts was investigated using gel and ion-exchange chromatography monitored by sequence-specific radioimmunoassays before and after incubation with trypsin, carboxypeptidase B, and arylsulfatase. Whereas the neural lobe contained only the bioactive alpha-carboxyamidated cholecystokinin (CCK) peptides (32 pmol/g), of which CCK-8 predominated, the anterior lobe contained substantial amounts of three large nonamidated procholecystokinin fragments (95 pmol/g; Mrs, 9000, 7000, and 5000) and small amounts of alpha-amidated CCK (8.3 pmol/g). The latter occurred only in the following large molecular forms: component I, CCK-58, and traces of CCK-33. Corticotrophic tumors processed the large forms to small CCK-8-like forms as are found in the brain and in the gut. The results show that a hormone gene, although translated, is expressed only to a limited extent as mature, active peptide outside the principal production region(s). Thus the processing of CCK to small alpha-amidated peptides in the less-differentiated tumor tissue supports the hypothesis that differentiation of endocrine cells may be sustained also at the posttranslational level.
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PMID:Preprocholecystokinin processing in the normal human anterior pituitary. 347 48

The immunological relationships among the proteins of the mosquito larvicidal toxin produced by Bacillus thuringiensis subsp. israelensis have been investigated by using polyclonal antisera specific for the 28-, 70-, and 135-kilodalton proteins. Each of these proteins was immunologically distinct. There was no cross-reaction among the three proteins and the two non-homologous antisera. Treatment of toxin proteins with larval gut enzymes for 20 h identified protease-resistant domains at approximately 65, 38, and 22 kilodaltons. Similar domains were generated by treatment with trypsin and chymotrypsin. Our immunological and kinetic data indicate that the 28-kilodalton protein is degraded successively to protein bands at 26, 25, 23, and 22 kilodaltons, the 70-kilodalton protein is degraded to a protein at 38 kilodaltons, and the 135-kilodalton protein is degraded successively to protein bands at 94, 72, and, probably, 65 kilodaltons. Solubilized toxin possesses two biological activities, larvicidal and general cytolytic (hemolytic). We used nondenaturing gel electrophoresis to show that the hemolytic activity resides in the 28-kilodalton protein. However, higher-molecular-weight proteins are required to achieve the level of toxicity observed in intact toxin.
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PMID:Immunological relationships among proteins making up the Bacillus thuringiensis subsp. israelensis crystalline toxin. 353 73

Raw soya flour (RSF) is thought to cause pancreatic hypertrophy in rats because trypsin inhibitor in the flour binds trypsin in the gut lumen and this lowering of free trypsin concentrations leads to the release of cholecystokinin (CCK). Intestinal enzyme concentrations were therefore studied in rats fed RSF for from one hour to 400 days to determine whether free trypsin concentrations were depressed during the period of pancreatic growth (up to six to eight weeks after starting RSF). Intestinal levels of enzymes were raised from one hour after starting the diet up to 400 days, indicating that stimulation of pancreatic secretion continued for as long as this diet was fed. Free trypsin concentrations were, however depressed only for the first 12 hours. It seems unlikely, therefore, that lowered free trypsin concentrations alone stimulate the release of CCK in these animals.
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PMID:Intestinal free trypsin concentrations fall only transiently when rats are fed raw soya flour. 369 15

We purified a peptide from rat pancreatic juice that enhances pancreatic enzyme secretion in a manner different from that of exogenous trypsin inhibitors, such as soybean trypsin inhibitor, when it is infused into the rat intestine. In this paper, we present evidence for the release of gut hormone(s) into the blood of rats after intestinal administration of the peptide. In the presence of atropine, an anesthetized rat small intestine was washed out with saline containing soybean trypsin inhibitor (Kunitz type) to eliminate proteases. Under these conditions, the rat small intestine was divided into four equal parts by ligation. Administration of the peptide into the first quarter of the small intestine stimulated pancreatic enzyme secretion. However, administration into the more distal parts did not stimulate the enzyme secretion. Moreover, intravenous injection of 1 mL of plasma from rats in which the peptide had been infused into the duodenum caused stimulation of pancreatic enzyme secretion in the recipient rats. It was suggested that the purified peptide acts in the proximal small intestine and that it stimulates the release of gut hormone(s) into the blood to enhance pancreatic enzyme secretion. These findings support the hypothesis that the peptide we purified is responsible in part for the humoral control of pancreatic enzyme secretion in the response to food intake.
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PMID:Stimulation of pancreatic enzyme secretion by a peptide purified from rat bile-pancreatic juice. 376 Oct 9

As part of a study designed to reveal information about molecular features of allergenic food proteins after absorption from the gut the specificity of antibodies in normal human serum to hen's egg ovalbumin was investigated using ELISA techniques. Preliminary investigations with monoclonal antibodies and hyperimmune rabbit antiserum specific for ovalbumin in its native and denatured form established that the molecule underwent an extensive conformational change on adsorption to polyvinyl chloride microtitre plates. The native conformation could be retained by using antibodies to couple the protein to the surface. Serum from 90% of healthy adult human donors contained IgG antibodies to ovalbumin. In nearly all cases the antibodies were specific predominantly for the native molecule and could not be absorbed with denatured ovalbumin or peptides prepared from it by cleavage with cyanogen bromide or trypsin. Antibodies to denatured ovalbumin were detected in most sera but at very low levels and were preferentially absorbed by the homologous antigen; peptides and native ovalbumin showing variable absorptive activity. Thus, although ovalbumin is ingested largely in a denatured form, the serum antibody response is stimulated mainly by topographic epitopes of the native molecule.
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PMID:Studies on the specificity of antibodies to ovalbumin in normal human serum: technical considerations in the use of ELISA methods. 381 2

The mechanisms by which FFA are absorbed by the gut are unclear. To examine these processes, binding of [14C]oleate to isolated rat jejunal microvillous membranes (MVM) was studied in vitro. When [14C]oleate alone or compounded with bovine serum albumin at various molar ratios was incubated with MVM aliquots, binding was time- and temperature-dependent, inhibitable by addition of excess cold oleate, and decreased by heat denaturation or trypsin digestion of the membranes. When [14C]oleate binding to heat denatured MVM, which increased continuously as a function of the free oleate concentration and was taken as a measure of nonspecific binding, was subtracted from total binding to native MVM, a curve suggestive of saturable specific binding was observed. In contrast to fatty acids, there was no specific binding of [14C]taurocholate or [35S]sulfobromophthalein to jejunal MVM. After MVM solubilization with 1% Triton X-100, affinity chromatography over oleate-agarose and elution with 7 M urea yielded a single 40,000-mol-wt protein. This Sudan Black/periodic acid-Schiff-stain-negative protein co-chromatographed on Sephadex G-100 with [14C]oleate, [14C]palmitate, [14C]arachidonate, and [14C]linoleate, but not with the [14C]oleate ester of cholesterol, [14C]phosphatidylcholine, [14C]taurocholate, or [35S]sulfobromophthalein. A rabbit antibody to the previously reported hepatic membrane fatty acid binding protein (FABP) gave a single line of immunologic identity between the FABPs of rat jejunum and rat liver membrane. It inhibited the binding of [14C]oleate to native MVM but not heat denatured MVM, and, in immunohistochemical studies, demonstrated the presence of the FABP in the apical and lateral portions of the brush border cells of the jejunum, but not on the luminal surface of esophagus or colon. These data are compatible with the hypothesis that a specific FABP plays a role in fatty acid absorption from the gut.
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PMID:Identification, isolation, and partial characterization of a fatty acid binding protein from rat jejunal microvillous membranes. 388 64


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