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)

Methoxypolyethylene glycol of molecular weight 5000 was converted to a reactive succinimidyl carbonate form (SC-PEG). The usefulness of this new polymeric reagent for the covalent attachment of polyethylene glycol to proteins was evaluated. SC-PEG was found to be sufficiently reactive to produce extensively modified proteins under mild conditions within 30 min, showing the highest reactivity around pH 9.3. The commonly used succinimidyl succinate derivative of methoxypolyethylene glycol (SS-PEG) served as a reference standard to which the new reagent was compared. The stability of the polymer-protein linkages, studied on a series of PEG-modified bovine serum albumins, provided the single most important difference between the two activated polymers. Urethane-linked PEG-proteins obtained through the use of SC-PEG showed considerably higher chemical stability than SS-PEG-derived conjugates. The measured rate constants of aminolysis (using N alpha-acetyllysine) and hydrolysis showed that SC-PEG is slightly less reactive yet more selective of the two reagents. Hydrolysis of the active groups on SC-PEG was on average twofold slower than that on SS-PEG. The differences in the rates of aminolysis were even smaller than those in hydrolysis. PEG-trypsin conjugates produced by both activated polymers showed similar properties: they had no proteolytic activity, well-preserved esterolytic activity, and enhanced activity toward p-nitroanilide substrates. Michaelis-Menten constants of the modified enzymes were determined using N alpha-benzyloxycarbonyl-L-arginine p-nitroanilide. These measurements indicated that the attachment of PEG to trypsin caused an increase in both the rate of turnover of the substrate and its affinity toward the modified enzymes. Through a series of experiments involving the appropriate polymeric and low-molecular-weight model compounds, it was demonstrated that these increases in amidolytic activity were unrelated to tyrosyl residues acylation by either one of the activated polymers.
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PMID:Evaluation of a new reagent for covalent attachment of polyethylene glycol to proteins. 155 Jun 59

We measured pancreatic enzyme and bicarbonate responses to graded doses of intravenous secretin or cerulein alone or together in healthy human subjects. Bicarbonate responses were steady and well maintained during the last 3.5 h of the 4 h of infusions of secretagogues, giving evidence for a constant pancreatic flow rate. Potentiation (more-than-additive response) was observed between secretin and cerulein for bicarbonate secretion, but not for enzyme secretion. Secretin stimulated pancreatic enzyme secretion. The effect was most pronounced with amylase secretion and less prominent with lipase, trypsin, and chymotrypsin secretion. Changes in the proportion of enzymes were seen over time, with trypsin and chymotrypsin output declining towards the end of cerulein infusion. We conclude that in humans the effects of secretin on pancreatic enzyme secretion are complex and include time-dependent changes in the enzyme mixture, but potentiation between secretin and cerulein does not occur for enzyme output.
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PMID:Pancreatic secretory responses to long-term infusions of secretin and cerulein in humans. 170 24

The biosynthesis of alpha-amidated peptides from their glycine-extended precursors is catalyzed by the sequential action of peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL). The two enzymes are part of a bifunctional, integral membrane protein precursor, peptidylglycine alpha-amidating monooxygenase (PAM). The major forms of PAM mRNA in the adult rat atrium differ by the presence or absence of optional exon A, a 315-nucleotide segment separating the PHM and PAL domains. Using antipeptide antibodies specific to the PHM, exon A, PAL, and cytoplasmic domains of rat PAM, carbonate-washed atrial membranes were found to contain proteins corresponding to rPAM-1 and rPAM-2. Digestion of atrial membranes with a variety of endoproteinases released PHM and PAL catalytic activities. Dose-response curves indicated that both catalytic activities were extremely resistant to inactivation by trypsin. Endoproteolytic digestion of atrial membranes with trypsin, chymotrypsin, elastase, thermolysin, or endoproteinase Lys-C generated a 35-kDa PHM fragment. Digestion with trypsin, elastase, thermolysin, or endoproteinase Lys-C generated a 42-kDa PAL fragment. In contrast to the stability exhibited by the PHM and PAL domains, the cytoplasmic domain of PAM was destroyed by most of the enzymes; only digestion with endoproteinase Lys-C generated a stable fragment. Digestion with endoproteinase Arg-C removed the carboxyl-terminal tail from PAM but failed to release the PHM or PAL domains from the membranes. The PHM fragments generated by some of the endoproteinases showed a tendency to adhere to the membranes. Thus the bifunctional PAM protein consists of independent catalytic domains separated from each other and from the putative transmembrane domain by flexible regions accessible to attack by a wide variety of endoproteinases.
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PMID:The membrane-bound bifunctional peptidylglycine alpha-amidating monooxygenase protein. Exploration of its domain structure through limited proteolysis. 189 99

Pancreatic secretion is involved in circadian regulation of the whole organism. This observation was obtained in animals and humans with pancreatic fistulas. We report on three patients in whom the pancreas was removed totally or subtotally because of chronic pancreatitis with severe pain. A segment of the removed gland was transplanted into the thigh in order to preserve endocrine function. The pancreatic duct was drained by a polyethylene tube until pancreatic duct occlusion. Postoperatively juice volume increased within 3 days and remained constant afterwards with 300 ml in 24 hours. Secretin, cholecystokinin and food intake are able to stimulate the transplanted segment in a typical manner. The secretion showed circadian changes. In all patients the pancreatic juice content of protein, amylase, trypsinogen, calcium, and zink decreased till 11 p.m. After 11 p.m. the content of all substances increased and reached maximal values at 6 a.m. Flow rates and therefore output per minute decreased greatly till 6 a.m. The large juice volume of 300 ml in 24 hours is perhaps the consequence of a break down of the feedback mechanism between intraduodenal trypsin activity and CCK-release. The changes during the night may be of pathogenetic relevance. In the early morning pancreatic juice is highly concentrated and the flow rate is very low. High protein concentrations, high calcium concentrations, and reduced flow rates may lead to protein and calcium carbonate precipitates. This mechanism is under discussion in the pathogenesis of chronic pancreatitis.
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PMID:[Exocrine function of a heterotopically transplanted pancreas segment in humans]. 195 40

Mechanisms of neural (vagal and cholinergic) and hormonal [cholecystokinin (CCK)] control of pancreatic exocrine secretion were studied in basal interdigestive conditions and after stimulation by an intraduodenal meal in rats equipped with a semichronic pancreatic fistula. Bile was recirculated into the duodenum, and a solution of trypsin and electrolytes was continuously infused. Pancreatic secretion was compared in control experiments, after vagotomy, and after venous infusion of cholinergic and CCK antagonists. Basal pancreatic secretion was decreased by atropine, pirenzepine, and hexamethonium and to a lesser extent by vagotomy (protein output decreased more than fluid and HCO3- outputs). The CCK antagonists L364,718 and lorglumide had no effect on basal interdigestive pancreatic secretion. Small doses of atropine (8 and 25 micrograms.kg-1.h-1) did not modify the cumulated pancreatic response to the meal, whereas larger doses (75 and 225 micrograms.kg-1.h-1) increased it by 40-85%, according to the variables. Pirenzepine and hexamethonium did not modify the pancreatic response. Vagotomy had no effect on fluid and HCO3- responses and tended to increase protein response. L364,718 and lorglumide completely inhibited the protein response and decreased the fluid and HCO3- responses by 75 and 40%, respectively. L364,718 also suppressed the increased pancreatic response induced by atropine. This work confirms the prominent role of neural cholinergic mechanisms in the control of basal interdigestive pancreatic secretion in rats. In contrast, the pancreatic protein response to an intraduodenal meal depends on CCK, whereas fluid and HCO3- responses also depend on other hormonal factors. Our results suggest that a muscarinic (probably M3) mechanism can decrease the postprandial CCK release independently of the pancreatic feedback control by trypsin.
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PMID:Control of interdigestive and intraduodenal meal-stimulated pancreatic secretion in rats. 197 89

Extracts from Xenopus eggs capable of nuclear envelope assembly in vitro were fractionated by differential and density gradient centrifugation. Nuclear envelope assembly was found to require soluble components in the cytosol and two distinct particulate fractions, which we have called nuclear envelope precursor fractions A and B (NEP-A and NEP-B). Both NEP-A and NEP-B are sensitive to treatments with trypsin, sodium carbonate, and detergents, but can be distinguished from each other by their sensitivities to high salt and N-ethylmaleimide and by their levels of alpha-glucosidase activity. Vesicles in NEP-B bind to chromatin, whereas those in NEP-A do not. NEP-B may therefore be involved in the targeting of membranes to the surface of the chromatin, whereas NEP-A may provide a pool of vesicles that contributes many of the nuclear envelope membranes. NEP-B may also play a role in the assembly of nuclear pore complexes because the density of nuclear pores in the resulting envelope is dependent on the ratio of NEP-B to NEP-A in the reconstituted extract.
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PMID:A distinct vesicle population targets membranes and pore complexes to the nuclear envelope in Xenopus eggs. 199 30

A purified protein fraction from a solubilized and trypsin-digested extract of Bacillus thuringiensis subsp. thuringiensis (HD-524) fermentation powder was lytic to cells from several lepidopteran lines. Maximum yield was obtained by alkaline carbonate-thiocyanate solubilization of washed powder followed by trypsin digestion and Sephacryl (S-300) chromatography. The alkaline carbonate-solubilized fraction consisted predominantly of two bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with MW of 144 +/- 0.9 kDa and 134 +/- 1.4 kDa. After trypsin treatment and column chromatography, the cytolytic fraction consisted of a major band with a MW of 60.0 +/- 1.8 kDa and a minor band of 69 +/- 0.9 kDa. Cells from Trichoplusia ni (TN368) were most susceptible to lysis with 50% of cells lysed at 3 micrograms/ml, followed by Spodoptera frugiperda cells (SF21AE) exhibiting 50% cell lysis at 5 micrograms/ml and Lymantria dispar cells (Ld652Y) showing 40% lysis at 10 micrograms/ml. Chemical modification of the polypeptides was performed to determine the role of certain amino acid residues in the cytolytic activity. The group-specific reagent tetranitromethane was used to nitrate and oxidize tyrosine and cysteine residues, respectively. Cysteine residues alone were also modified with p-hydroxymercuribenzoic acid. Lysine residues were modified with O-methylisourea. Of the three types of amino acid residues, only the modification of tyrosine resulted in reduced cell lysis.
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PMID:Chemical modification of Bacillus thuringiensis subsp. thuringiensis (HD-524) trypsin-activated endotoxin: implication of tyrosine residues in lepidopteran cell lysis. 200 42

Plasma membranes were purified from flagella of porcine cauda epididymal sperm and proteolytic regulation of bicarbonate-sensitive adenylate cyclase was studied. It was found that the epididymal sperm plasma membrane contained a trypsin-like proteinase which inactivated adenylate cyclase. Bicarbonate activates adenylate cyclase as reported previously, but, at the same time, the anions enhance the inactivation of the enzyme by the membrane-bound trypsin-like proteinase. This phenomenon is not due to the direct activation of the proteinase, but closely related to the activation of adenylate cyclase by bicarbonate. It was also found that seminal proteinase inhibitors blocked the inactivation of adenylate cyclase and maintained the bicarbonate activation of the enzyme at high level. Actually, bicarbonate keeps adenylate cyclase fully active in ejaculated sperm, because membrane-bound proteinase is completely inhibited by the seminal proteinase inhibitors. These results suggest that the interactions between membrane-bound proteinase and seminal proteinase inhibitor are involved in the regulation of the bicarbonate-sensitive adenylate cyclase system.
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PMID:Effects of a membrane-bound trypsin-like proteinase and seminal proteinase inhibitors on the bicarbonate-sensitive adenylate cyclase in porcine sperm plasma membranes. 216 77

By means of consecutive pancreatic stimulation, we have investigated the presence of changes of pancreatic function in alcoholic patients, with and without alcoholic liver disease, in order to detect functional alterations and possible association of hepatic and pancreatic disease. The patients were 49 chronic alcoholics (8 patients without liver disease, 11 hepatic steatosis, 9 alcoholic hepatitis and 21 alcoholic cirrhosis) and 15 non alcoholic subjects (8 normal controls and 7 cases of non alcoholic cirrhosis). In all the cases two consecutive stimulations were carried out: first with secretin and cholecystokinin (CCK) and second with CCK alone. The total volume and concentration as well as the output of bicarbonate, trypsin, amylase and total proteins were measured in the duodenal juice. Patients with alcoholic cirrhosis had larger volumes of duodenal juice and lower concentrations of bicarbonate, enzymes and proteins. There was also a tendency to larger volume and lower bicarbonate concentration as the hepatic lesion was more severe. Bicarbonate output was significatively higher in patients with alcoholic cirrhosis but for the remaining parameters the outputs were similar in all the groups. In conclusion, the alterations in pancreatic function parallel the severity of the liver disease. None of the patients had changes consistent with chronic pancreatitis.
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PMID:[Changes in pancreatic secretion in alcoholic liver disease]. 237 59

Recurrent calculi of the main bile way may be recurrent or residual. Recurrent stones are yellow-brown, crumbly and earthy and contain high quantities of calcium palmitate; residual stones, on the other hand, are firmer, round or berry-like, usually faceted and contain cholesterol, bilirubinate and carbonate of calcium (aragonite, vaterite, etc.) but never palmitate. Residual stones at times also present a peripheral "shell" presenting palmitate and this shows that a new component determined by bile changes is added to the cholesterol stone, which represents the central core, because of stasis and biliary infection. The distinction of calculi into residual and recurrent is also made on the basis of the classic morphologic and clinical criteria described in the literature, also and above all on the basis of specific, objective scientific criteria deriving from in-depth clinical study of the patient, the chemical study of the bile, morphological, mineralogical and structural study of the stone. The following are considered in particular: instrumental examinations made during hospitalisation and operation; pH, enzymatic activity (phospholipase, trypsin and amylase) and examination of bile cultures; morphological, microscopic examination (electronic scan microscopy) and mineralogical examination (X-ray diffractometry and infrared spectroscopy) of the calculus. A personal series of recurrent calculosis of the main biliary way is considered, special attention being paid to a case that was particularly interesting in relation to the fact lithiasic recurrence occurred just 10 months after the previous operation and the fact that biliary stasis was not determined by stenosis of the papilla which proved fully patent.
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PMID:[Our experience with recurrent biliary calculosis after cholecystectomy]. 239 59


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