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)

In rat liver cells isolated by perfusion in the perfusion in the presence of collagenase, the major portion of cytochrome P-450 is present in the oxidized, nonsubstrate-bound, low spin state. Drug addition to a suspension of liver cells results in the rapid formation of the cytochrome P-450 (Fe3+)-substrate complex which in turn is followed by the appearance of other species with different spectral characteristics before steady state drug monooxygenation is achieved. Cytochrome P-450-linked metabolism of various tested drugs and carcinogenic polycyclic hydrocarbons by isolated rat liver cells is as fast, or faster, as with rat liver microsomes supplemented with a NADPH generating system. Both experimental models respond similarily to phenobarbital or 3-methylcholanthrene pretreatment of the animals and to various of the wellknown inhibitors of drug metabolism. Except with liver cells isolated from fasted, phenobarbital-treated rats, generation of cytosolic NADPH seems sufficient to support optimal drug metabolism even in the absence of added substrates of intermediary metabolism. In isolated liver cells oxidized drug metabolites undergo subsequent metabolic conversion, most often to form the corresponding glucuronides and sulphates. These are readily excreted, whereas non-conjugated products, e.g. free phenols, tend to accumulate intracellularly. Cellular glucuronide formation is strongly inhibited by ethanol-presumably due to an unfavorable effect of the increased NADH/NAD+ ratio on the synthesis of uridine-5'-diphosphoglucuronic acid (UDPGA). In contrast, low concentrations of ethanol have no, or only a slight stimulatory effect on the cytochrome P-450-linked step of drug metabolism and there are indications that the oxidation of low concentrations of ethanol is in fact stimulated by a facilitated reoxidation of cytosolic NADH occuring during drug monooxygenation.
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PMID:Recent studies on cytochrome P-450-linked functions in isolated rat liver cells. 0 26

Although the alpha-adrenergic antagonist phentolamine potentiates glucose-stimulated insulin secretion of intact animals, it either does not alter, or it inhibits in vitro insulin secretion. This may be because in the higher concentration used in in vitro studies, phentolamine exerts a second pharmacological effect that counterbalances its primary effect of blocking monoamine action. We recently demonstrated that pancreatic islets contain substantial amounts of monoamine oxidase (MAO), and that MAO inhibitors such as iproniazid and tranylcypromine can alter insulin secretion. In the present study, we determined if other drugs that affect insulin secretion, alter the MAO activity of homogenates of rabbit pancreatic islets (collagenase technique) or liver. Phentolamine, phenoxybenzamine and propranolol (10 muM and 100 muM) inhibit islet and hepatic MAO. Haloperidol (10muM) inhibits hepatic but not islet MAO, while haloperidol (10muM) does not inhibit MAO in either tissue. Ethanol (270 to 2.7mM) inhibits islet MAO. Hepatic MAO is inhibited by high (270 to 180mM) but not by low (27 to 2.7mM) concentrations of ethanol. Collagenase digestion does not increase the sensitivity of islet and liver MAO to inhibition by phentolamine or ethanol. In the absence of added monoamines, phentolamine and phenoxybenzamine do not alter basal or glucose-stimulated insulin secretion from rabbit pancreas. Preincubation of rabbit pancreas with the serotonin precursor 5-hydroxytryptophan (5-HTP) increases the beta cell serotonin content and inhibits glucose-stimulated insulin secretion. Alpha adrenergic antagonists not only fail to block, but actually potentiate the serotonin inhibition of insulin secretion. We conclude that inhibition of islet MAO may cause an increase in islet monoamine content and these monoamines may alter in vitro insulin secretion. One mechanism through which adrenergic antagonists and ethanol modify in vitro insulin secretion may be by inhibiting pancreatic islet MAO.
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PMID:Inhibition of pancreatic islet monoamine oxidase by adrenergic antagonists and ethanol. 0 95

From the supernatant of B. melaninogenicus ss. asaccharolyticus culture, a protein fraction was isolated by ethanol precipitation. The fraction was tested for the presence of clotting and fibrinolytic activities by application of quantitative techniques and specific substrates for measurement of prothrombin and plasminogen activation, and collagenase and elastase activity. It is postulated that ability of Bacteroides melaninogenicus ss. asaccharolyticus extracellular factors to clot fibrinogen and activate plasminogen, are due to a limited proteolysis by the proteolytic enzymes produced by this microorganism and not to the existence of specific B. melaninogenicus coagulase of plasminogen activator.
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PMID:The nature of clotting and fibrinolytic activities of Bacteroids melaninogenicus. 2 65

Native cuticle collagen, obtained from Nereis virens, was incubated with purified bacterial collagenase (EC 3.4.4.19). The kinetics of proteolysis were monitored by viscometry, in parallel with similar digestions of calf skin collagen. Comparison of the kinetics of digestion of the two collagens, at similar enzyme to substrate ratios (w/w), showed that the native cuticle collagen was relatively refractory to digestion by bacterial collagenase. Characterization of the cuticle collagen digest by sodium dodecyl sulfate-polyacrylamide electrophoresis and agarose gel filtration in CaCl2 showed a large polypeptide, of about 300,000 daltons, to be a major product. The native form of this product, a unique fragment, was isolated from the digest by ethanol precipitation. It was found to have an intrinsic viscosity of 120 dl/g, to have an optical rotary dispersion curve characteristic of collagen, to undergo a typical collagenous thermal transition with a Tm of 23.2 degrees, and to have a calculated molar mass of 900,000 g with molecular dimensions of 9,000 X 13 A. It had an amino acid composition which was similar, but not identical with the native cuticle collagen. Although the original substrate contained two dissimilar chains, A and B, in a molar ratio of 1:2, the collagenase-resistant product appeared to be composed of only one type of polypeptide fragment. Possibly, the original subunits contain similar, if not identical collagenase-resistant regions.
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PMID:Nereis cuticle collagen. Isolation and properties of a large fragment resistant to proteolysis by bacterial collagenase. 19 99

The surface saccharide composition of collagenase-dispersed pancreatic cells from adult guinea pig and rat glands was examined by using eight lectins and their ferritin conjugates: Concanavalin A (ConA); Lens culinaris (LCL); Lotus tetragonolobus (LTL); Ricinus communis agglutinins I and II (RCA I, RCA II); Soybean agglutinin (SBA); Ulex europeus lectin (UEL); and wheat germ agglutinin (WGA). Binding studies of iodinated lectins and lectin-ferritin conjugates both revealed one population of saturable, high-affinity receptor sites on the total cell population (approximately 95% acinar cells). Electron microscopy, however, revealed differences in lectin-ferritin binding to the plasmalemma of acinar, centroacinar, and endocrine cells. Whereas acinar cells bound heavily all lectin conjugates, endocrine and centroacinar cells were densely labeled only by ConA, LCL, WGA, and RCA I, and possessed few receptors for LTL, UEL, and SBA. Endocrine and centroacinar cells could be differentiated from each other by using RCA II, which binds to centroacinar cells but not to endocrine cells. Some RCA II receptors appeared to be glycolipids because they were extracted by ethanol and chloroform-methanol in contrast to WGA receptors which resisted solvent treatment but were partly removed by papain digestion. RCA I receptors were affected by neither treatment. The apparent absence of receptors for SBA on endocrine and centroacinar cells, and for RCA II on endocrine cells, was reversed by neuraminidase digestion, which suggested masking of lectin receptors by sialic acid. The absence of LTL and UEL receptors on endocrine and centroacinar cells was not reversed by neuraminidase. We suggest that the differential lectin-binding patterns observed on acinar, centroacinar, and endocrine cells from the adult pancreas surface-carbohydrate-developmental programs expressed during morphogenesis and cytodifferentiation of the gland.
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PMID:Distribution of cell surface saccharides on pancreatic cells. II. Lectin-labeling patterns on mature guinea pig and rat pancreatic cells. 42 54

The effect of ethanol feeding for a period of 6 months on parameters of hepatic collagen metabolism was studied in the rat. Ethanol feeding resulted in small increases in the fibrous and ground substance components of hepatic collagen as measured by increases in collagen-bound hydroxyproline and hexosamine, respectively. Liver histology revealagen proline hydroxylase and the incorporation of labeled proline into collagen by liver slices, both of which are associated with collagen synthesis, were not changed. Ethanol feeding resulted in increases in the concentration of protein and deoxyribonucleic acid in the Kupffer cells, but in no changes in collagenase activity. An increase in collagen degradation was suggested, however, by the increase in the urinary excretion of hydroxyproline and glycosaminoglycans found after 2 and 6 months of ethanol feeding, respectively. This study demonstrates that fatty infiltration of the liver in the rat, after prolonged ethanol feeding, is associated with increased deposition of chemically detectable collagen and evidence of increased collagen degradation, although no significant changes in parameters associated with hepatic collagen synthesis were found.
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PMID:Changes in hepatic collagen metabolism in rats produced by chronic ethanol feeding. 55 49

Rat hepatocytes were freshly prepared from adult animals using the collagenase-perfusion technique. The hepatic transport of thiamine was studied in isolated liver cells. The process was found to be saturable with an apparent Kt of 0.31 mM and a V max of 0.7 mumoles/ml intracellular fluid/5 minutes. However, at higher substrate concentrations, the process proceeded in a linear fashion. Both pyrithiamine and oxythiamine were inhibitory on the hepatic uptake of thiamine, the latter showed much weaker activity than the former. The system required the presence of sodium ions and was sensitive to ouabain. Anaerobic condition and metabolic inhibitors, e.g., 2,4-dinitrophenol, cyanide, and iodoacetate suppressed the uptake rate of thiamine. Addition of ethanol in the incubation medium also caused significant reduction of thiamine uptake. Efflux studies indicated that a portion of intracellular thiamine is readily available for exodus. Chromatographic analyses showed that thiamine was only slightly metabolically altered during the transport process. It is suggested that thiamine is transported into isolated hepatic cells by an active, sodium-dependent process.
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PMID:Active transport of thiamine by freshly isolated rat hepatocytes. 71 32

A chromatographic method is developed for quantitative estimation of the collagenase-like enzyme (CLE) activity in extract of adenohypophysis and in preparations obtained during various steps of the enzyme isolation. The enzymatic hydrolysis of Cbz-Gly-Pro-Ala-Gly-Pro-Gly-OCH3 in presence of 2-mercaptoethanol at pH 8.0 was used as a pattern. The products formed were separated by chromatography on the paper; then they were stained with ninhydrin and converted into cupric complexes during extraction with ethanol; the optic density was measured at 510 nm. The optimal conditions for the enzymatic reaction were established. The method enabled to estimate the CLE activity in presence of prolyl carboxypeptidase. The specific effect of the CLE purified preparation on various synthetic peptides is discussed.
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PMID:[Chromatographic method of determining the activity of the collagenase-like enzyme of the adenohypophysis and several findings concerning the specificity of its action]. 88 63

Percutaneous liver biopsies obtained from patients with a history of chronic alcoholism and normal liver, fatty liver, alcoholic hepatitis, or active cirrhosis were incubated with tritiated proline to determine the pattern of collagen biosynthesis in these conditions. Incorporation of labeled proline and hydroxyproline into salt-soluble and insoluble fractions of collagen was evaluated by radiochemical analysis and tissue localization documented by autoradiography. Biopsy specimens of alcoholic hepatitis and cirrhosis exhibit a significant increase in the amount of radioactive proline and hydroxyproline in salt-soluble and insoluble collagen. Marked accumulation of radioactivity occurred over bile ducts, fibroblasts, and collagen fibers in the portal area and over hepatocytes, fibroblasts, and collagen fibers in the centrilobular area. Fatty liver is associated with an increase in uptake of proline and hydroxyproline in the salt-soluble fraction of collagem; silver grains appear in the periphery of fat-laden cells and in areas of focal inflammation. Digestion by collagenase indicates that labeling over fibroblasts and collagen reflects active synthesis, whereas, entry of proline into the cell protein pool is responsible for accumulation of radioactivity in other sites. In vitro ethanol causes a significant increase in the incorporation of proline and hydroxyproline into collagen in biopsy specimens of alcoholic hepatitis or active cirrhosis, but has no effect on collagen synthesis by normal or fatty liver.
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PMID:Collagen biosynthesis in liver disease of the alcoholic. 117 Feb 67

The existence and significance of Von Korff fibers during early dentinogenesis are still very controversial. The purpose of the present study was to re-examine the questions of the existence, nature and significance of Von Korff's fibers using light microscopy and immunohistochemistry. Specimens were obtained from 3 days-old CD-I mice and mandibles were carefully dissected under constant irrigation and immediately fixed in 10% neutral buffered formalin for light microscopy. Sections were treated or not with collagenase prior to silver staining. For immunohistochemistry, specimens were fixed in 95% ethanol and embedded in paraffin. Sections were reacted with goat anti-human-bovine type I or type III collagen and a rhodamine (RITC) labelled rabbit anti-goat IgG was then reacted as a secondary antibody. Slides were then examined under a Zeiss II photomicroscope equipped with epifluorescence. Our results have confirmed the presence of argyrophilic material concentrated at the periphery of the dental papilla and stretching from the subodontoblastic layer to the future dentino enamel junction. The distribution of type III collagen was very similar to the distribution of the silver staining at the cervical loop area. Type I collagen distribution was different and concentrated in areas where odontoblasts were fully differentiated. Our study showed that Von Korff fibers are not artefactual. We have established the presence of an apical compartment containing type I collagen fibers and a basal compartment containing type III collagen to explain the image of continuous silver staining crossing the entire thickness of the odontoblast layer.
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PMID:Investigation of the role of Von Korff fibers during murine dentinogenesis. 128 7


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