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

---

Query: EC:4.2.2.7 (heparinase)
1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Org 10172 provided adequate anticoagulation for this patient. An excellent correlation between anti-factor Xa activity and ACT was observed at the doses used for CPB. If high-dose Org 10172 is used, these data suggest that it may be possible to circumvent the measurement of anti-factor Xa activity by using the ACT as an index of this heparinoid's anticoagulant effect. Because postoperative bleeding may be excessive, however, development of a method of reversal of Org 10172 is desirable. Although the optimal ACT, dose, plasma concentration, and means of reversal (e.g., protamine vs. heparinase) remains to be determined, heparinoids provide an alternate means of anticoagulation for CPB in patients unable to receive standard heparin.
...
PMID:"Heparin-free" cardiopulmonary bypass: first reported use of heparinoid (Org 10172) to provide anticoagulation for cardiopulmonary bypass. 169 48

A 77-kDa complex of thrombin and a protein secreted by activated platelets had little if any thrombin amidolytic activity, indicating that the secreted protein is an inhibitor. The molecular weight of the inhibitor before reaction with thrombin was approximately 50,000. The apparent second-order rate constant for complex formation was estimated to be 1.3 x 10(6) M-1 s-1 (mean of four measurements); it was not affected by heparin or heparinase. These properties distinguish this inhibitor from other protease inhibitors secreted by platelets. The inhibitor reacted with trypsin and possibly with urokinase but not with factor Xa.
...
PMID:Characteristics of a thrombin inhibitor secreted by activated platelets. 210 89

Low molecular weight heparins from a variety of commercial sources were examined. These had been prepared by several methods including peroxidative cleavage, nitrous acid cleavage, chemical beta-elimination, enzymatic beta-elimination, and chromatographic fractionation. The molecular weight and polydispersity of these low molecular weight heparins showed greater differences than were observed for typical commercial heparin preparations. Considerable differences were also observed in the antithrombin III mediated anti factor Xa activity, the heparin cofactor II mediated antifactor IIa activity, and the USP activity of these low molecular weight heparins. An oligosaccharide-mapping technique (comparable to the peptide mapping of proteins) was applied to these low molecular weight heparins in an effort to understand the structural features responsible for their activity differences. Heparin lyase from Flavobacterium heparinum was first used to depolymerize the low molecular weight heparin into its constituent oligosaccharides. The oligosaccharides present in the resultant mixture were identified and quantitated by using standard oligosaccharides of defined structure on gradient polyacrylamide gel electrophoresis and strong anion exchange high pressure liquid chromatography. Six of the oligosaccharide products have been identified and represent nearly 90 wt % of heparin's mass. Even though all the low molecular weight heparins showed these six oligosaccharide components, their content in each varied greatly, accounting for 20 to over 90% of their mass. The antithrombin III mediated anti factor Xa activities of the low molecular weight heparins correlated only poorly to the concentration of a hexasaccharide containing a portion of heparin's antithrombin III binding site. The heparin cofactor II mediated antifactor IIa activity, however, could not be correlated to these six oligosaccharides of known structure nor to the molecular weight or charge density of these low molecular weight heparins. The low molecular weight heparins prepared by different methods each showed a new distinctive oligosaccharide in their maps. Their isolation and structural characterization, which included two-dimensional NMR and fast atom bombardment mass spectrometry, indicated that these unusual oligosaccharides result from end-sugar modification during chemical depolymerization. Both gel electrophoresis and high-pressure liquid chromatography mapping techniques showed a greater structural diversity between low molecular weight heparins than had previously been observed between similarly analyzed commercial heparins.
...
PMID:Oligosaccharide mapping of low molecular weight heparins: structure and activity differences. 216 May 37

The structure of the glycosaminoglycan chain of a heparan sulfate proteoglycan isolated from the conditioned medium of an endothelial cell line has been analyzed by using various degradative enzymes (heparitinase I, heparitinase II, heparinase, glycuronidase, sulfatases) from Flavobacterium heparinum. This proteoglycan inhibits the thromboplastin-activated pathway of coagulation; as a consequence, the catalytic conversion of prothrombin to thrombin is arrested. Heparitinase I (EC 4.2.2.8), an enzyme with specificity restricted to the heparan sulfate portion of the polysaccharide, releases fragments with the electrophoretic mobility and the structure of heparin. Conversely, an assessment of the size and distribution of the heparan sulfate regions has been provided by the use of heparinase (EC 4.2.2.7), which, by degrading the heparin sections of the chain, releases two segments that exhibit the structure of heparan sulfate. One of these segments is attached to the protein core. On the basis of these findings, the heparan sulfate chain can be defined as a copolymer containing heparin regions in its structure. The combined use of these enzymes has made it possible to establish the disaccharide sequence of parts of the glycosaminoglycan moiety of this proteoglycan.
...
PMID:Heparin sequences in the heparan sulfate chains of an endothelial cell proteoglycan. 295 57

The ascitic form of a chemically-induced pancreatic ductal adenocarcinoma in the Syrian golden hamster was very bloody and indistinguishable from blood macroscopically. Unlike blood, the bloody fluid remained unclotted at room temperature. To explore the possibility of presence of anticoagulants, we mixed 40% cell-free fluid with 60% normal human plasma and tested the clottability of the mixture with standard techniques. Plasma containing the fluid showed markedly prolonged activated partial thromboplastin time (APTT), thrombin time (TT) and recalcification time (RCT), and normal prothrombin time (PT) and reptilase time (RT). Comparing the prolongation of APTT of samples containing the fluid to those containing a commercial heparin, the fluid contained an anticoagulant activity equivalent to 0.436 +/- 0.03 unit heparin per ml (mean +/- SEM, n = 14). In addition to prolonging the APTT, TT and RCT, the fluid also inhibited the clotting and amidolytic activities of thrombin. "Heparsorb" had nearly completely neutralized the anticoagulant activity in fluid samples, while protamine sulfate was only partially effective. Incubation of fluid with pronase or phospholipase did not affect its anticoagulant activity; incubation with heparinase had only a minimal effect. Electrophoresis of an alkali digested fluid on cellulose acetate revealed the presence of heparan sulfate. The native ascitic fluid also contained other hemostatic components including platelets, fibrinogen and antithrombin III, but their concentrations were much lower than in blood. Apparently, heparan sulfate in the neoplastic effusion is largely responsible for the bloody ascites tumor remaining unclotted.
...
PMID:Anticoagulant activity in cell-free peritoneal fluid of an experimental pancreatic ascites tumor. 300 55

Studies were conducted to define the location of components and sequences in heparin with respect to their distance from the peptide linkage in the native proteoglycan. A purified heparin-oligopeptide was linked via its amino terminus to a matrix containing an azo bond and an activated carboxyl group. The polysaccharide chain was maximally degraded, either with heparinase or nitrous acid, and the soluble products were removed. The heparin-oligopeptide fragments that remained on the matrix were released by reductive cleavage of the azo linkage and characterized. The fragments, as well as heparin released without prior degradation, contained serine and glycine as the principal amino acids; the ratio of galactose to xylose was 2:1. The ratio of glucosamine to serine of 33:1 in the undegraded heparin was reduced to 6:1 and 1:1 in the heparinase-treated and nitrous acid-treated products, respectively. The undegraded sample and the fragments contained phosphate in equivalent amounts, demonstrating its presence in the heparin-protein linkage region. The heparin-oligopeptide preparation was also fractionated by gel filtration and high and low molecular weight fractions thus obtained were each linked to the insoluble matrix. The products that were subsequently released were subfractionated on a molecular weight-calibrated column of Sephadex G-200, and eluates were assayed for activity in promoting the neutralization of thrombin and factor Xa by antithrombin. The results revealed a sharp decrease in specific activity in heparin-oligopeptide fractions below Mr = 15,000 indicating that the anticoagulant-conferring segment is located at about 20 disaccharide units away from the peptide linkage region.
...
PMID:Location of specific oligosaccharides in heparin in terms of their distance from the protein linkage region in the native proteoglycan. 333 97

We have previously shown that angiogenesis inhibition and tumor regression can be accomplished by combinations of heparin or heparin fragments with cortisone [Folkman, J., Langer, R., Linhardt, R. J., Haudenschild, C. & Taylor, S. (1983) Science 221, 719-725]. Oral heparin was also effective in combination with cortisone. We now show that a single oral dose of [35S]heparin or [3H]heparin (15,000 units/kg) results in continuous release of radioactive material into the bloodstream for at least 12 hr. This is associated with the presence of anti-factor Xa activity at a level of approximately equal to 0.1 unit/ml. The radioactive material is identified as oligo-, di-, and monosaccharides by its behavior in chromatographic systems, its possession of anti-factor Xa activity, and the effect of treatment with bacterial heparinase. The heparin fragments are extensively metabolized to fragments without anti-factor Xa activity that are readily subject to urinary excretion.
...
PMID:Oral heparin results in the appearance of heparin fragments in the plasma of rats. 345 56

To control blood levels of heparin during extracorporeal therapy, the use of a blood filter containing heparinase, a heparin-specific enzyme that cleaves heparin to small fragments with less anticoagulant activity, has been proposed. These fragments have anti-factor Xa activity but no anti-thrombin activity. The potential toxicity of heparin fragments as compared to heparin was examined in rats by identifying presumptive sites of drug-related toxicity by whole-body autoradiography and by histological examination of major organs. Radioautograms of rats sacrificed 5 hr after dosing with [35S]heparin fragments indicated no potential targets different from what was observed in rats dosed with [35S]heparin. In addition, the faster urinary clearance of heparin fragments resulted in a lower concentration of these fragments than of heparin in all common target organs. No hemorrhages or other lesions were found in rats injected intravenously with heparin fragments (100 mg/kg) and sacrificed after 5 hr. In addition, no mortality or delayed toxic effects were observed in a similar group of animals sacrificed 2 weeks after dosing. In contrast, 80% of rats injected with heparin (100 mg/kg) showed hemorrhages of the lungs at the time of necropsy.
...
PMID:Comparative studies of heparin and heparin fragments: distribution and toxicity in the rat. 373 75

Bovine antithrombin III (AT III) interaction with the luminal surface of bovine aortic segments with a continuous layer of endothelium was examined. Incubation of 125I-AT III with vessel segments, previously washed free of endogenous AT III, demonstrated specific, time-dependent binding to the protease inhibitor to the endothelium. Half-maximal binding was observed at an added AT III concentration of 14 nM. Binding of 125I-AT III to the vessel wall was reversible (50% dissociated in 4 min), and addition of either heparin or Factor Xa accelerated displacement of 125I-AT III from the vessel segment. Dissociation of 125I-AT III from the vessel segment in the presence of factor Xa coincided with the formation of a Factor Xa-125I-AT III complex. Inactivation of Factor IXa and Factor Xa by AT III was facilitated in the presence of vessel segments. Pretreatment of vessel segments with highly purified Flavobacterium heparinase precluded the vessel-dependent augmentation of AT III anticoagulant activity as well as specific binding of 125I-AT III to the vessel endothelium. In contrast, pretreatment of the vessel segments with chrondroitinases (ABC or AC) had no detectable effect on 125I-AT III binding or on AT III anticoagulant activity. AT III binding to vessel segments was competitively inhibited by increasing concentration of platelet factor 4. Binding of the protease inhibitor to vessel segments was inhibited by chemical modification of AT III lysyl or tryptophan residues. These AT III derivatives retained progressive inhibitory activity. These data suggest that heparin-like molecules are present on the aortic vessel wall and mediate binding of AT III to the vessel surface, as well as enhancing the anticoagulant activity of AT III at these sites.
...
PMID:Interaction of antithrombin III with bovine aortic segments. Role of heparin in binding and enhanced anticoagulant activity. 396 7

15 heparin preparations from bovine intestine, pancreas and lung and hog intestine were fractionated in two main components by selective barium precipitation. The ones that precipitated at room temperature with barium (slow moving (SM)-heparins) had a high anticoagulant activity measured by the USP and APTT (activated partial thromboplastin time) assay and low antithrombotic activity by the Yin and Wessler method. The fractions precipitated at 5 degrees C with barium (fast moving (FM)-heparins) had a low anticoagulant action and high antithrombotic activity. The maximum anti-Xa activity (chromogenic method) was present in heparins with molecular weights around 12-15 X 10(3) daltons whereas high APTT and LPL releasing activities were present in SM-heparins with molecular weights of 30-40 X 10(3) and 15-25 X 10(3) daltons, respectively. FM-heparins had a higher anti-Xa activity and lower lipoprotein lipase (LPL)-releasing activity when compared with the SM-heparins with the same molecular weights. Significant structural differences were observed between SM- and FM-heparins by 13C-NMR spectra and enzymatic degradation with heparinase and heparitinase from Flavobacterium heparinum. Also, significant differences were observed for anti-Xa and anticoagulant activities for the two types of heparins depending on the pharmacological assay used.
...
PMID:Fractionation and structural features of two heparin families with high antithrombotic, antilipemic and anticoagulant activities. 407 37


1 2 3 4 5 6 Next >>

---