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

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.
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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.
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PMID:Anticoagulant activity in cell-free peritoneal fluid of an experimental pancreatic ascites tumor. 300 55

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.
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PMID:Fractionation and structural features of two heparin families with high antithrombotic, antilipemic and anticoagulant activities. 407 37

An 8-month-old male with acute monoblastic leukemia died during induction chemotherapy of severe bleeding refractory to repeated infusions of platelets and clotting factors. A heparin effect was suggested by prothrombin time (PT) of 26 seconds, partial thromboplastin time (PTT) of 94 seconds, thrombin time 240 seconds, and reptilase time 18.4 seconds, with a fibrinogen of 88 mg/dl. Both plasma mixed with the patient's urine and the patient's plasma had their thrombin times corrected toward normal by both PF4 and protamine. Synergism of the anticoagulant with antithrombin III was demonstrated not only by enhanced inhibition of thrombin but also by an increased rate of formation of thrombin--antithrombin III complexes in the presence of the anticoagulant, which was eliminated by preincubation with heparinase. Since the anticoagulant activity was not found in the blasts themselves, it is presumed that the anticoagulant is heparin/heparan liberated from the endothelial lining by products of the cell destruction secondary to chemotherapy.
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PMID:A heparin-like anticoagulant in an 8-month-old boy with acute monoblastic leukemia. 658 79

Finback-whale (Balaenoptera physalus L.) heparin was partially digested with a purified heparinase and an octasaccharide with high affinity for antithrombin III was isolated from the digest by gel filtration, followed by affinity chromatography on a column of antithrombin III immobilized on Sepharose 4B. This octasaccharide possessed high inhibitory activity for Factor Xa in the presence of antithrombin III, but was essentially inactive for thrombin-antithrombin III reaction. The anticoagulant activity determined by the activated-partial-thromboplastin-time method was very low (40-70 units/mg), although the initial whale heparin exhibited high activity (252 units/mg). On the basis of the results of chemical analyses, 13C n.m.r. spectrum and enzymic studies with purified heparinase, heparitinases 1 and 2, the predominant structure of the octasaccharide was proposed as follows: delta UA(2S) alpha 1 leads to 4GlcNS alpha 1 leads to 4IdUA alpha 1 leads to 4GlcNAc(6S) alpha 1 leads to 4GlcUA beta 1 leads to 4GlcNS(3S) alpha 1 leads to 4IdUA(2S) alpha 1 leads to 4GlcNS. Comparing this structure with those of the heparin octasaccharides so far reported, the presence of the critical structural elements for binding to antithrombin III was suggested in the pentasaccharide region situated at the reducing end of this octasaccharide. Binding to antithrombin III of the critical structural elements alone would appear to elicit the acceleration of the Factor Xa-antithrombin III reaction. Additional structural elements required for the acceleration of the thrombin-antithrombin III reaction and for the manifestation of high anticoagulant activity are discussed.
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PMID:Structure and biological activity of finback-whale (Balaenoptera physalus L.) heparin octasaccharide. Chemical, carbon-13 nuclear-magnetic-resonance, enzymic and biological studies. 712 78

Porcine intestinal heparin was partially digested with a purified heparinase and an octasaccharide with high-affinity for antithrombin III was isolated from the digest by gel filtration, followed by affinity chromatography on a column of Sepharose 4B coupled with antithrombin III. The anticoagulant activity determined by the activated partial thromboplastin time method of the octasaccharide was 240 units/mg. Fifty percent inactivation activities of the octasaccharide for thrombin and factor Xa in the presence of antithrombin III were 2 and 6.5 times, respectively, higher than those of the initial heparin. These data indicate that the octasaccharide possesses the critical structural integrities required for manifesting these biological activities.
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PMID:Anticoagulant activity of heparin octasaccharide. 733 23

Artifactual heparin contamination of blood samples drawn for coagulation testing is an ongoing problem. A retrospective analysis of activated partial thromboplastin times (APTTs) greater than 45 seconds from patients on neither heparin nor Coumadin (Dupont, Wilmington, DE) therapy shows complete correction of the APTT to normal in 39% of such samples after treatment with heparinase. Recheck of samples with significantly prolonged APTTs after treatment with heparinase is proposed as the best method to avoid inappropriate transfusion of fresh frozen plasma.
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PMID:Heparin contamination in coagulation testing and a protocol to avoid it and the risk of inappropriate FFP transfusion. 757 96

A whole blood hemostasis system (Hepcon) provides both activated clotting time and accurate whole blood heparin concentration measurements via an automated protamine titration method. This study was designed to prospectively evaluate the impact of heparin and protamine administration using this system on the incidence and treatment of bleeding after cardiopulmonary bypass. Two hundred fifty-four patients requiring cardiopulmonary bypass were enrolled in this prospective study over a 7-month period. Patients treated with antifibrinolytic agents (aprotinin, epsilon-aminocaproic or tranexamic acid) were excluded. Patients were randomly assigned to either a control (n = 127) or intervention (n = 127) group. For control patients, the anticoagulation protocol consisted of an initial fixed dose of 250 U/kg of heparin, and additional 5000 U heparin doses were administered if the activated clotting time was less than 480 seconds. Heparin was neutralized with an initial fixed dose of protamine (0.8 mg protamine per milligram total heparin). For the intervention group, an initial dose of heparin was based on an automated heparin dose-response assay. Additional heparin doses were administered if the heparin concentration was less than the reference concentration or for an activated clotting time less than 480 seconds. The protamine dose was based on the residual heparin concentration. Treatment of excessive bleeding after cardiopulmonary bypass was based on an algorithm using point-of-care testing with whole blood prothrombin time, activated partial thromboplastin time, heparinase activated clotting time, and platelet count. No differences between the two treatment groups were identified in reference to demographic factors, preoperative anticoagulant medications, preoperative coagulation data, number of reoperations, or combined procedures and duration of cardiopulmonary bypass. Indirect evidence for coagulation factor consumption was demonstrated in control patients by more prolonged whole blood prothrombin time and activated partial thromboplastin time values after cardiopulmonary bypass when compared with values obtained in the intervention group. Patients in the intervention cohort received greater doses of heparin (intervention: 612 +/- 147, control: 462 +/- 114 U/kg, p < 0.0001) and had lower protamine to heparin ratios (intervention: 0.70 +/- 0.64, control: 0.94 +/- 0.21, p = 0.0001) compared with control patients. Patients in the intervention cohort received significantly fewer platelet (intervention: 1.7 +/- 3.6 U, control: 3.7 +/- 6.7 U, p = 0.003), plasma (intervention: 0.4 +/- 1.3 U, control: 1.4 +/- 2.5 U, p = 0.0001), and cryoprecipitate units (intervention: 0.0 +/- 0.0 U, control: 0.2 +/- 1.2 U, p = 0.04) during the perioperative interval than control patients.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The impact of heparin concentration and activated clotting time monitoring on blood conservation. A prospective, randomized evaluation in patients undergoing cardiac operation. 858 30

A clinician's concern about an erratic response to oral anticoagulation in a patient treated concurrently with heparin and warfarin led the authors to investigate the effect of heparin on INR values obtained with various commercial thromboplastin reagents. Studies conducted with pooled normal plasma and with pooled plasma from patients treated long-term with oral anticoagulants demonstrated a wide range of sensitivities to heparin of these reagents as characterized by prolongation of INR values. Innovin was unaffected by concentrations of heparin as high as 1 U/mL. In contrast, Ortho thromboplastin showed the greatest increase in INR values over the range of heparin concentrations studied. Three other thromboplastins including Neoplastine CI, Dade thromboplastin, and Simplastin A demonstrated only limited sensitivity to heparin. Prolongation of the INR by heparin was reversed by protamine in a dose-related manner and also by preincubation of the plasma with heparinase. Some patients treated with warfarin while on the authors' institutional protocol for heparin had plasma concentrations greater than 0.8 U/mL. When thromboplastin reagents sensitive to heparin were used with such specimens, the INR values obtained were falsely elevated. The authors suggest that reagents insensitive to heparin be employed to avoid this difficulty.
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PMID:Heparin-induced increase in the international normalized ratio. Responses of 10 commercial thromboplastin reagents. 885 47

This study was designed to evaluate the potential in vitro use of heparinase to eliminate functionally active heparin prior to performing whole blood (WB) prothrombin time (PT) and activated partial thromboplastin time (APTT) assays. A total of 250 U/kg of heparin for cardiopulmonary bypass (CPB) was administered to 30 cardiac surgical patients in three consecutive, divided doses (20, 80, and 150 U/kg) at 15-min intervals. Blood specimens were obtained prior to heparin administration (baseline) and 10 min after each heparin dose. After collection, blood specimens were fractionated into three aliquots of which the first was used for determination of heparin concentration. After gentle mixing, WB PT and APTT measurements were performed for heparinase (Aliquot 2)- and nonheparinase (Aliquot 3)-treated blood. With consecutive heparin doses of 20 and 80 U/kg, WB PT increased from a baseline of 12.3 +/- 0.1 s to 13.3 +/- 0.2 and 18.5 +/- 1.3 s, while WB APTT increased from a baseline of 28.3 +/- 1.1 s to 89.5 +/- 5.4 after the initial heparin dose (20 U/kg). When compared to baseline (no heparin) results, small, progressive increases in heparinase-treated WB PT (0.7 +/- 0.1, 1.5 +/- 0.1, 2.1 +/- 0.1 s) and APTT (2.3 +/- 0.3, 5.7 +/- 0.4, 9.5 +/- 0.5 s) were seen with increasing heparin concentration (0.23, 1.58, and 3.95 U/mL, respectively). Heparinase was highly effective in eliminating the anticoagulant effects of even large amounts of heparin in plasma from cardiac surgical patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:In vitro reversal of heparin effect with heparinase: evaluation with whole blood prothrombin time and activated partial thromboplastin time in cardiac surgical patients. 794 73


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