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)

We differentiate indirect and direct methods. The indirect methods include the examination of the blood (ESR, blood picture, electrolytes, especially calcium, for the exclusion of hyperparathyroidism, status of fat and liver enzymes, activity of alpha-amylase and lipase. More informative than a serum determination is the measurement of the amylase activity in the 24-hour urine. The detection of chymotrypsin in the stool can be recommended as an investigative test also for use in general practive in collaboration with a central laboratory.- The direct methods include investigation of the duodenal juice with measurement of pH, bicarbonate, of the activities of chymotrypsin, trypsin, lipase and amylase. For excluding of a disturbance of the carbohydrate metabolism in addition to blood sugar determinations, glucose tolerance and tolbutamide tests, the determination of insulin activity is indicated.
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PMID:[Chemical Investigation of Chronic Pancreatitis]. 0 30

A membrane fraction enriched in parathyroid hormone (PTH)-sensitive adenylate cyclase and sodium and potassium ion-activated (Na+, K+)-ATPase was prepared from bovine kidney. Tritiated PTH binding to this membrane fraction was dependent on both hormone and membrane protein concentration. Both total and specific binding of the hormone decreased significantly after 5 to 10 min of incubation at 22 degrees. PTH binding was highly specific, being sensitive to inhibition only with active forms of unlabeled hormone (native and 1-34 PTH). Specific binding showed a pH optimum of 7.3 to 7.5. Inhibition of binding of tritiated hormone by unlabeled PTH was also highly effective at pH 6.0, but this apparently specific binding was also inhibited by adrenocorticotropic hormone, insulin, glucagon, and vasopressin. Dissociation of bound hormone was demonstrated, and an apparent dissociation constant of 4.6 X 10(-2) min-1 was obtained. Specific binding was eliminated by pretreatment of the membranes with trypsin. The concentration dependence for inhibition of binding with unlabeled PTH was identical to that for activation of adenylate cyclase in this membrane preparation, and binding was also inhibited by concentrations of calcium in the 0.5 to 2 mM range.
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PMID:Binding of tritiated bovine parathyroid hormone to plasma membranes from bovine kidney cortex. 1 29

Mammary tumor cell growth factor(s) has been identified in extracts of platelets from both male and female rats, as well as in extracts prepared from pooled outdated human platelets. When assayed by the growth promotion of MTW9/PL rat mammary tumor cells in culture, platelet extracts alone were able to support growth 50--75% as well as whole serum. The mitogenic activity from crude human platelet lysates was shown to be trypsin sensitive, relatively stable to extremes of pH, labile to heat treatment at 70 degrees, non-dialysable, ammonium sulfate precipitable, not removed by 56 degrees charcoal treatment, and of apparent molecular weight of 30,000 to 50,000 daltons as estimated by G-100 Sephadex chromatography. The platelet derived mammary growth factor activity was not replaced or potentiated by thrombin or known hormones and growth factors such as prolactin, insulin, 17-beta-estradiol, progesterone, hydrocortisone, L-thyroxine, and mouse epidermal growth factor. The experimental report demonstrates that platelets are a rich source growth factor activity for rat epithelial mammary tumor cells, and that the activity appears to be a polypeptide(s) different from other mitogenic activities known to influence growth of mammary tissue.
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PMID:Platelet derived growth factor(s) for a hormone-responsive rat mammary tumor cell line. 3 Jul 82

Factor D (C3 proactivator convertase) of human serum has been shown to be absolutely necessary for alternative pathway function, for activation of the C3/C5 convertase of that pathway and not to be a subunit of this enzyme. Factor D was found to be present in human plasma in active form only, at a concentration of 2 microgram/ml, and not to be controlled by plasma protease inhibitors or by spontaneous decay. Unlike trypsin, factor D cleaves and activates factor B only when it is in Mg++-dependent complex with C3b, has no esterolytic activity, and is unable to cleave the B chain of insulin. The alleged functional and antigenic relationship of factor D to alpha-thrombin could not be verified. The results of this study led to the description of the mechanism of action of factor D in terms of the cryptic site hypothesis.
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PMID:Mechanism of action of factor D of the alternative complement pathway. 8 4

The role of the surrounding membrane structure on the binding characteristics of the insulin receptor was studied by using several digestive enzymes. The effects observed with particulate membrane preparations are compared with those from soluble receptor preparations. beta-Galactosidase and neuraminidase had no effect on insulin binding to either particulate or soluble receptors from human placentae. Exposure to 2 units of phospholipase C/ml increased insulin binding to particulate membranes, but was without effect on the soluble receptor preparation. The increase in binding to particulate membranes was shown to be due to an increase in apparent receptor number. After 5 min exposure to 500 microgram of trypsin/ml there was an increase in insulin binding to the particulate membrane fraction, owing to an increase in receptor affinity. After 15 min exposure to this amount of trypsin, binding decreased, owing to a progressive decrease in receptor availability. In contrast, this concentration of trypsin had no effect on the solubilized receptor preparation. Because of the differential effects of phospholipase C and trypsin on the particulate compared with the solubilized receptor preparations, it is concluded that the effects of these enzymes were due to an effect on the surrounding membrane structure. Changes in receptor configuration due to alterations within the adjoining membrane provide a potential mechanism for mediating short-term alterations in receptor function.
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PMID:The effects of digestive enzymes on characteristics of placental insulin receptor. Comparison of particulate and soluble receptor preparations. 10 Jan 6

Partially purified beta cell monolayer cultures were prepared from the pancrease of neonatal Wistar rats by dissociating the cells with a trypsin-collagenase solution. The cultures were grown in medium 199 containing a 10% fetal calf serum and 100 or 300 mg/100 ml glucose. Insulin release from the primary cultures during 12 days was 15 to 20 microunit/culture/day when the cells were grown in the medium containing 300 mg/100 ml glucose. When glucose concentration in the medium was decreased from 300 to 100 mg/ml insulin release fell to 2--5 microunit/culture/day. Theophylline stimulated insulin release in a short-time experiment. Transplantation of a 6--8-day culture in diabetic rats reduced the blood glucose concentration for 1 to 2 days.
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PMID:[Monolayer culture of pancreatic beta cells of newborn rats: Insulin secretion in vitro and attempt at beta-cell transplantation in experimental diabetes]. 15 May 94

The insulin or proinsulin response of the isolated rat adipocyte was destroyed by preincubation with trypsin. After 120 minutes, biological responsiveness partially regenerated. Similarly, the biological responsiveness of the isolated fat cell to non-suppressible insulin-like activity (NSILA) was only partially destroyed following trypsin digestion, and did not regenerate. In contrast to the above, cyclic AMP or dibutyryl cyclic AMP effects were unaltered by trypsin or neuraminidase digestion.
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PMID:Studies of the biological activity of insulin, cyclic nucleotides and concanavalin A in the isolated fat cell. 16 39

Insulin has been isolated from pancreases of the Syrian hamster and from a transplantable islet-cell tumor of the hamster. Acid/ethanol extraction, ether precipitation, ion exchange and gel filtration chromatography gave preparations of suitable purity for structural studies. Using trypsin cleavage, automatic Edman degradation and manual Edman degradation, a complete sequence of the pancreatic insulin B chain was determined. By automatic Edman degradation, the amino-terminal 10 residues of the pancreatic A chain were assigned and the sequence of carboxy-terminal eleven residues could be deduced by homology to other mammalian and avian insulins. The sequence assigned to hamster insulin A chain is identical to that of the rat, mouse and spiny mouse. The sequence of hamster insulin B chain is identical to rabbit and spiny mouse B chain. In terms of protein evolution, hamster insulin thus appears to occupy an intermediate position between rabbit and rat insulins. Amino acid composition, tryptic peptide composition and partial sequence analysis of the hamster tumor insulin showed no differences from hamster pancreatic insulin.
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PMID:A comparison of the structure of hamster pancreatic insulin and insulin extracted from a transplantable hamster islet-cell carcinoma. 17 43

The binding and the velocity of degradation of 125I-insulin in the absence or presence of varying concentrations of native procline insulin were studied using isolated rat hepatocytes. At insulin concentrations ranging from 5 X 10(-11) to 10(-6) M, insulin degradation velocity showed a first order dependence on the total concentration of insulin bound at steady state. The overall reaction had an apparent rate constant of 0.030 +/- 0.011 min-1. Furthermore, the degradation of a given amount of 125I-insulin bound to cells was more rapid and extensive than the degradation of the same amount of insulin which had been newly exposed to fresh cells. Mid pretreatment of isolated hepatocytes with trypsin or chymotrypsin at concentrations of 5 to 20 mug/ml depressed to the same degree the amount of 125-I-insulin bound at steady state and the 125I-insulin degradation velocity. Peptide or protein hormones unrelated to insulin, including the oxidized A and B chains of insulin, failed to depress the amount of insulin bound or the velocity of insulin degradation when present at concentrations of 10-5 or 10-6 M. Over a wide range of concentrations, various synthetic insulin analogues and naturally occurring insulins depressed to the same degree the amount of 125I-insulin bound at steady state and the 125I-insulin degradation velocity. These observations suggest that insulin bound to hepatocyte plasma membranes is the substrate for insulin degradation by the liver.
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PMID:Binding and degradation of 125I-insulin by rat hepatocytes. 17 97

It was previously shown that the fibroblast surface antigen (SF antigen, SFA) is composed of polypeptides of high molecular weight 210,000 (SF210) and 145,000 (SF145) and that both of these decrease in quantity after transformation of the fibroblasts by Rous sarcoma virus (RSV). The present experiments show that SF210 is a glycoprotein. It is accessible to surface labelling by lactoperoxidase catalyzed iodination. The SF210 molecule is highly susceptible to trypsin on cell surface. Anti-SFA antibodies specifically precipitated the surface labelled polypeptide. The lactoperoxidase iodinated SF210 polypeptide was greatly reduced in cells transformed by RSV. It is concluded from these studies that the large external transformation sensitive (LETS) protein detected by other workers is the same molecule as SF210. Part of the label of surface iodinated fibroblasts did not enter the polyacrylamide gels. This high molecular weight material is also susceptible to trypsin treatment and decreases in quantity after transformation by RSV. The data suggest that it may be antigenically related to SF protein. Treatment of surface of 35S-methionine-labelled cultures with trypsin in concentrations able to initiate proliferation of density-inhibited cells rapidly released SF210 from fibroblast surface. A single high molecular weight polypeptide (mol. wt about 200,000, SF200) was detected in the culture medium. SF210 may thus be a major target molecule of trypsin action. Treatment of cultures with insulin that also stimulated the fibroblasts to initiate proliferation did not result in any detectable alteration in the external glycoprotein SF210. It is concluded that although release of SF210 may be a sufficient trigger to stimulate proliferation in stationary cells, this molecule appears not to be directly involved in initiation of fibroblast proliferation from the G1 (or G0) phase of the cell cycle.
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PMID:Fibroblast surface antigen (SF): the external glycoprotein lost in proteolytic stimulation and maligant transfromation. 17 31


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