Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.2.2.7 (heparinase)
 1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glycosaminoglycans, including heparin, have been demonstrated both in vitro and in vivo to protect the ischemic myocardium against reperfusion injury. In the present study, we sought to determine whether the cardioprotective effects of heparin administration could be reversed by the heparin-degrading enzyme heparinase. New Zealand white rabbits were pretreated with heparin (300 U/kg i.v.) or vehicle (saline). Two hours after treatment, hearts were removed, perfused on a Langendorff apparatus, and subjected to 25 min of global ischemia, followed by 45 min of reperfusion. Hemodynamic variables were obtained before ischemia (baseline) and every 10 min throughout the reperfusion period. Compared with vehicle-treated rabbits, the left ventricular end-diastolic and left ventricular developed pressures were improved significantly (p <.05) in the heparin-treated group. Ex vivo administration of heparinase (5 U/ml) immediately before the onset of global ischemia was associated with a reversal of the heparin-mediated cardioprotection. The uptake of a radiolabeled antibody to the intracellular protein myosin and creatine kinase release were used to determine membrane integrity and discriminate between viable and nonviable myocardial tissue. The uptake of radiolabeled antimyosin antibody and release of creatine kinase after reperfusion were increased in heparin-pretreated hearts exposed to heparinase, indicating a loss of membrane integrity and increased myocyte injury. These results demonstrate that neutralization of heparin by heparinase promotes increased myocardial injury after reperfusion of the ischemic myocardium.
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PMID:Ex vivo reversal of heparin-mediated cardioprotection by heparinase after ischemia and reperfusion. 1045 76

Two techniques for determining enzyme kinetic constants using isothermal titration microcalorimetry are presented. The methods are based on the proportionality between the rate of a reaction and the thermal power (heat/time) generated. (i) An enzyme can be titrated with increasing amounts of substrate, while pseudo-first-order conditions are maintained. (ii) Following a single injection, the change in thermal power as substrate is depleted can be continuously monitored. Both methods allow highly precise kinetic characterization in a single experiment and can be used to measure enzyme inhibition. Applicability is demonstrated using a representative enzyme from each EC classification, including (i) oxidation-reduction activity of DHFR (EC 1.5.1.3); (ii) transferase activity of creatine phosphokinase (EC 2.7.3.2) and hexokinase (EC 2.7.1.1); (iii) hydrolytic activity of Helicobacter pylori urease (EC 3.5.1.5), trypsin (EC 3.4.21.4), and the HIV-1 protease (EC 3.4.21.16); (iv) lyase activity of heparinase (EC 4.1.1.7); and (v) ligase activity of pyruvate carboxylate (EC 6.4.1.1). This nondestructive method is completely general, enabling precise analysis of reactions in spectroscopically opaque solutions, using physiological substrates. Such a universal assay may have wide applicability in functional genomics.
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PMID:Enzyme kinetics determined using calorimetry: a general assay for enzyme activity? 1155 13

IBT 9302 (heparinase III, EC 4.2.2.8), purified from Flavobacterium heparinum, selectively cleaves heparan sulfate proteoglycans (HSPGs) from cellular surfaces and extracellular matrices. HSPGs serve as binding sites for P- and L-selectins, as well as for pro-inflammatory chemokines, such as interleukin (IL)-8. IBT 9302 reversibly removes these binding sites and inflammatory mediators, thereby limiting tissue damage following reperfusion of ischaemic areas by reducing leukocyte rolling, adhesion and extravasation. In models of myocardial ischaemia/reperfusion injury, infusion of IBT 9302 the time of transport and reperfusions, reduces the area of necrosis/area at risk ratios relative to vehicle-treated animals. Cardioprotection is accompanied by a reduction in serum creatine kinase levels and neutrophil adherence to coronary vessels, and the preservation of endothelial relaxation responsiveness to acetylcholine. HSPGs also serve as accumulation sites for most growth factors and IBT 9302 limits both proliferation and migration of vascular smooth muscle cells to platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and endothelial growth factor (EGF). In vivo, the application of IBT 9302 at the time of vascular injury significantly reduces arterial medial proliferation. External application of IBT 9302 to wounds in a steroid-impaired wound healing model increases tensile strength by releasing mitogenic growth factors and HSPGs from the surrounding extracellular matrix. Pharmacokinetic studies show a simple monoexponential decay following iv. bolus dosing of IBT 9302, with a half-life of 5 - 6 min. The majority of [(125)I]-IBT 9302 goes to the liver (60%) and kidneys (25%), following iv. dosing. Preliminary toxicology studies in rats following single iv. bolus (10 mg/kg) or infusion (10 mug/kg/min) dosing show no untoward effects. These results suggest that IBT 9302 may have therapeutic utility in treating myocardial ischaemia/reperfusion injury, ischaemic stroke, restenosis or in healing diabetic ulcer wounds, by virtue of its ability to selectively cleave HSPGs.
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PMID:IBT 9302 (Heparinase III): a novel enzyme for the management of reperfusion injury-related vascular damage, restenosis and wound healing. 1599 12