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:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two insoluble non-collagenous glycoprotein fractions (A and G) have been separated from puppy rib cartilage, following extraction of most of the proteoglycan and digestion of the insoluble residue with purified collagenase. After reduction, alkylation and extraction with sodium dodecylsulfate most of each protein is solubilized. Gel electrophoresis of solubilized A or G shows the presence of either one or two bands and gel chromatography shows both high and low molecular weight peaks. The production of a low molecular weight electrophoresis band from the high molecular weight Sephadex fraction indicates that there is aggregation and disaggregation of sub-units in sodium dodecylsulfate. Both A and G are high in aspartate plus glutamate and have a low hydroxyproline content. The insoluble A and G both contain hexose, uronic acid, galactosamine, glucosamine and a small amount of sialic acid, but they differ in their contents of hexose and six amino acids. They both form single bands in CsCl gradients but they differ in density. Electron microscopy shows that both insoluble glycoprotein fractions stain with lead, ruthenium red, or alcian blue plus phosphotungstate and that G contains many fine filaments. Material with the same appearance and staining properties was found to occur on the surface of collagen fibres in the undigested cartilage residue.
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PMID:Insoluble non-collagenous cartilage glycoproteins with aggregating sub-units. 16 54

The isolation of tubules and cells from human kidney cortex was realized by an enzymatic method. Tubules and cells were released from slices of kidney cortex by collagenase. The yield amounted to 80 % of the wet weight of incubated cortex slices. Thus numerous experiments with isolated tubules from one organ could be performed. Glucose production from different substrates was measured in order to test the biochemical integrity of the isolated cells. The highest rates of glucose formation were obtained with fructose as precursor. Glucose production was higher from lactate than from pyruvate. With proline and glutamine as substrates only small amounts of glucose were produced. Glucose formation from 10 mmol/1 pyruvate was linear with time up to 80 minutes. Ado-3':5'-P stimulated glucose formation at 10 mumolar concentration and inhibited gluconeogenesis at 1 mmolar, 0.1 mmolar and 1 mumolar concentrations.
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PMID:[An enzymatic method for the isolation of tubules and cells from human kidney cortex]. 16 42

In order to study the oeffect of somatostatin on the endocrine pancreas directly, islets isolated from rat pancreas by collagenase were incubated for 2 hrs 1) at 50 and 200 mg/100 ml glucose in the absence and presence of somatostatin (1, 10 and 100 mg/ml) and2) at 200 mg/100 ml glucose together with glucagon (5 mug/ml), with or without somatostatin (100 ng/ml). Immunologically measurable insulin was determined in the incubation media at 0, 1 and 2 hrs. Insulin release was not statistically affected by any concentration stomatostatin. On the other hand, somatostatin exerted a significant inhibitory action on glucagon-potentiated insulin secretion (mean +/- SEM, mu1/2 hrs/10 islets: glucose and glucagon: 1253 +/- 92; glucose, glucagon and somatostatin: 786 +/- 76). The insulin output in th epresence of glucose, glucagon and somatostatin was also significantly smaller than in thepresence of glucose alone (1104 +/- 126) or of glucose and somatostatin (1061 +/- 122). The failure of somatostatin to affect glucose-stimulated release of insulin from isolated islets contrasts its inhibitory action on insulin secretion as observed in the isolated perfused pancreas and in vivo. This discrepancy might be ascribed to the isolation procedure using collagenase. However, somatostatin inhibited glucagon-potentiated insulin secretion in isolated islets which resulted in even lower insulin levels than obtained in the parallel experiments without glucagon. It is concluded that the hormone of the alpha cells, or the cyclic AMP system, might play a part in the machanism of somatostatin-induced inhibition of insulin release from the beta-cell.
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PMID:Somatostatin-induced inhibition of insulin secretion from isolated islets of rat pancreas in presence of glucagon. 16 38

The inhibitory actions of somatostatin (100 ng./ml.) on insulin release, stimulated by high glucose (20 mM), and on glucagon release, stimulated by arginine (15 mM), were studied with two in vitro systems: the isolated perifused rat islets prepared by the collagenase procedure and the isolated perfused rat pancreas. Suppression of arginine-induced glucagon release by glucose (20 mM) and glyceraldehyde (5 mM) was also assessed in both systems. With the perfused pancreas, somatostatin caused 32 per cent inhibition of glucose-mediated insulin release and inhibited arginine-induced glucagon release by 72 per cent. In the same system, glucose and glyceraldehyde were similarly potent inhibitors of arginine-induced glucagon secretion. In contrast to the isolated perfused pancreas, there was no significant somatostation suppression of glucose-induced insulin release or arginine-induced glucagon release whether the inhibitor was present prior to or was added during stimulation by glucose or arginine. Furthermore, glucose was only minimally active and glyceraldehyde ineffective in inhibiting glucagon secretion due to arginine in the perifusion system. The most plausible explanation for the difference in the endocrine response of islet cells in the two types of widely used in vitro systems is that the alpha and beta cells have lost inhibitory receptors in the plasma membrane as a result of the collagenase isolation technic.
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PMID:Comparison of alpha- and beta-cell secretory responses in islets isolated with collagenase and in the isolated perfused pancreas of rats. 17 Nov 90

Pancreatic islets of wistar rats, isolated after 15 min of digestion with collagenase, secreted insulin in response to 15.0 mM glucose within 2 min and showed the typical sigmoidal glucose response during an incubation time of 15 and 60 min, respectively. Islets, isolated after 35 min of digestion with collagenase, responded with delay after stimulation with glucose (after 15 min of incubation), and are characterized by an increased "release" in the presence of 2.5 mM glucose.
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PMID:[The effect of preparative pancreatic digestion with collagenase on the glucose stimulated insulin secretion of isolated Langerhans islets]. 17 95

Epithelial cells from the epididymis were released by digesting the chopped epididymis with pronase followed by collagenase plus hyaluronidase. The epithelial cells were further separated from contaminating cell types by differential centrifugation and sedimentation at unit gravity through a gradient of sucrose in Ringer. The isolated cells remained viable as judged by the exclusion of trypan blue. The cells respired in the presence of glucose and the rate of respiration was not altered by the subsequent addition of pyruvate.
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PMID:The isolation of epithelial cells from the rat epididymis. 17 76

A human pancreatic beta cell tumor was maintained in monolayer cell culture for 80 days. The culture was terminated because of bacterial infection. Probably because extensive trypsin-collagenase dissociation was unnecessary, the dissociated cells attached much more quickly to the surface of the culture flask than do rat pancreatic cells obtained by enzymatic dissociation. Insulin release not only oscillated widely during the first 40 days of culture but also showed a decline from 380 mU the first week to about 50 mU/week the seventh week. For some unknown reason fibroblast overgrowth was not a major problem. Reduction of the medium glucose concentration from 16.5 mM to 5.5 mM did not alter insulin release rate. At glucose concentration of 16.5 mM, somatostatin 1.0 mug/ml reduced insulin release by 40%. From our previously reported studies on the effect of somatostatin on insulin release by monolayer cell cultures of rat endocrine pancreas, we conclude that the constant release of insulin by the tumor cells is relatively nonstimulated. We have confirmed that monolayer cultures of human pancreatic beta cell tumor do not represent a good model for normal human beta cell function because of the major shortcoming of an apparent inability to recognize glucose as a secretogogue.
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PMID:Monolayer cell culture of human pancreatic beta cell tumor: effect of glucose and somatostatin on insulin release. 17 3

Pancreatic islets of Wistar rats were prepared by digestion with collagenase and then washed and isolated at three different temperatures (4, 22 and 37 degrees C). The efficiency of washing with regard to proteolytic and collagenolytic activities in the wash buffer was not affected by the temperatures used. The islet thiol:protein-disulphide oxidoreductase activity (EC 1.8.4.2) was apparently unchanged, whereas washing temperatures lower than 37 degrees C resulted in a diminished insulin content. The insulin secretion of islets, isolated at 4 degrees C, is reduced in response to glucose without changing the sigmoidal shape of dose-response curve.
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PMID:Investigations on isolated islets of Langerhans in vitro. Influence of temperature changes during preparation on some parameters of insulin metabolism. 17 3

1. Guinea-pig hepatocytes were prepared by collagenase digestion of the perfused liver. 2. The highest rates of gluconeogenesis were obtained from fructose, followed by pyruvate, xylitol and lactate, glycerol and propionate in that order. Maximum rates of gluconeogenesis were attained at 6-10mm substrate. 3. An initial 15-min lag period occurred during gluconeogenesis from lactate. This lag was abolished by preincubating the cells or by preincubation plus the addition of NH(4)Cl or lysine. 4. The lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were increased during the lag and adjusted to values favouring rapid gluconeogenesis from lactate after 15min. 5. The data suggest that the low glucose synthesis during the lag resulted from a limitation of the glutamate-aspartate shuttle and from the unusual redox state of the NAD(+) couple prevailing during this period. 6. At 0.1mm, amino-oxyacetate, a transaminase inhibitor, decreased gluconeogenesis from lactate by 80%, but had a negligible effect on glucose production from pyruvate. Gluconeogenesis from lactate was also inhibited (20%) by 10mm-dl-3-hydroxybutyrate.
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PMID:Gluconeogenesis by isolated guinea-pig liver parenchymal cells. 17 3

Exposure of hamster pancreatic islets to hyaluronidase during isolation by means of collagenase inhibits the insulinotropic action of several chemically different sulfonylureas, leucine, and glucagon without affecting glucose-stimulated insulin secretion. This inhibition is reversible for tolbutamide and leucine but irreversible for glucagon. Hyaluronidase inhibits reversibly the insulinotropic action of tolbutamide without affecting that of glucose also in mouse and rat isolated pancreatic islets . These findings suggest the existence of functionally related pancreatic beta cell receptors for tolbutamide and leucine different from those for glucose and glucagon and illustrate the potential usefulness of hyaluronidase as an enzymatic probe applicable toward investigating the cellular mechanism of action of key insulinotropic agents.
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PMID:Hyaluronidase-induced inhibition of the insulinotropic action of sulfonylureas, leucine, and glucagon in rodent isolated pancreatic islets. 17 48


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