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1.
Daisuke Miyazawa Atsushi Ikemoto Yoichi Fujii Harumi Okuyama 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2003,1631(1):17-25
We have shown previously that the phospholipase A (PLA) activity specific for phosphatidic acid (PA) in porcine platelet membranes is of the A1 type (PA-PLA1) [J. Biol. Chem. 259 (1984) 5083]. In the present study, the PA-PLA1 was solubilized in Triton X-100 from membranes pre-treated with 1 M NaCl, and purified 280-fold from platelet homogenates by sequential chromatography on blue-Toyopearl, red-Toyopearl, DEAE-Toyopearl, green-agarose, brown-agarose, polylysine-agarose, palmitoyl-CoA-agarose and blue-5PW columns. In the presence of 0.1% Triton X-100 in the assay mixture, the partially purified enzyme hydrolyzed the acyl group from the sn-1 position of PA independently of Ca2+ and was highly specific for PA; phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositol (PI) were poor substrates. The enzyme exhibited lysophospholipase activity for l-acyl-lysoPA at 7% of the activity for PA hydrolysis but no lipase activity was observed for triacylglycerol (TG) and diacylglycerol (DG). At 0.025% Triton X-100, the enzyme exhibited the highest activity, and PA was the best substrate, but PE was also hydrolyzed substantially. The partially purified PA-PLA1 in porcine platelet membranes was shown to be different from previously purified and cloned phospholipases and lipases by comparing the sensitivities to a reducing agent, a serine-esterase inhibitor, a PLA2 inhibitor, a Ca2+-independent phospholipase A2 inhibitor, and a DG lipase inhibitor. 相似文献
2.
The goal of this study was to synthesize a macromolecular probe of the TXA2 receptor antagonist BM13.505 which is unable to penetrate the platelet membrane for localization and characterization of the TXA2 receptor. The active NHS-ester of BM13.505 was synthesized and purified. It was used for covalent coupling of BM13.505 to bovine serum albumin, a macromolecular carrier. Inhibitory effects of free and macromolecular bound BM13.505 on aggregatory properties of U46619-stimulated platelets were measured and compared to TXA2 generation in platelets, as determined by TXB2 radioimmuno assay. No inhibitory effects of free and macromolecular-bound BM13.505 on ADP- or thrombin-induced platelet aggregation were observed. Equimolar concentrations of free or macromolecular bound BM13.505 inhibited U46619-induced platelet aggregation and TXA2 generation with equal potency. IC50-values for platelet aggregation inhibition by free and macromolecular bound BM13.505 were 64 nM and 96 nM respectively. It appears that the TXA2 receptor ligand binding site is located close to the outer membrane surface of platelets. Interaction of macromolecular bound BM13.505 with the platelet thromboxane receptor does not depend on the availability of the free carboxyl residue in BM13.505. The method for coupling a TXA2 receptor antagonist to a macromolecule will aid in constructing probes for the localization and characterization of the TXA2 receptor. 相似文献
3.
Chaoho Ouyang Tur-Fu Huang 《Biochimica et Biophysica Acta (BBA)/General Subjects》1983,757(3):332-341
Using DEAE-Sephadex A-50 column chromatography and gel filtration, a potent platelet aggregation inhibitor from Trimeresurus gramineus venom was purified. It was an acidic phospholipase a, rich in aspartic acid, glutamic acid and half-cystine, with an isoelectric point of 3.6. At a concentration of 10 μg/ml, the purified inhibitor showed a marked inhibitory effect on platelet aggregations induced by adenosine diphosphate, collagen, sodium arachidonate and ionophore A-23187 in rabbit platelet-rich plasma, washed platelet suspension, as well as in thrombin-degranulated platelet suspension. The ID50 of this venom inhibitor was about 2.5–5 μg/ml in platelet aggregations induced by all these aggregation inducers. The action of this inhibitor could be partially antagonized by phosphatidylethanolamine. High concentration of Ca2+ (5 mM) did not reverse the inhibitory action even in the presence of ionophore A-238187. The [14C]serotonin release induced by sodium arachidonate and thrombin was unaffected. Malonic dialdehyde formation induced by these aggregation inducers remained unchanged. Basal and prostaglandin E1-stimulated cAMP levels were not altered by this inhibitor. No lactate dehydrogenase was released even at a concentration of 62.5 μg/ml. Polylysine-induced platelet agglutination was not affected. β-Mercaptoethanol inactivated both its phospholiase A enzymatic and platelet inhibitory activities, while p-bromophenacyl bromide only inactivated the former activity. The possibility of acting on a common final step of platelet aggregation, i.e. the intercellular adhesion between the activated platelets, was proposed. 相似文献
4.
Chaoho Ouyang Tur-Fu Huang 《Biochimica et Biophysica Acta (BBA)/General Subjects》1983,761(2):126-134
A potent platelet aggregation inducer (platelet aggregoserpentin) was purified from Trimeresurus gramineus snake venom by DEAE-Sephadex A-50 and Sepharyl S-300 column chromatography. It was homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It elicited dose-dependently platelet aggregation and serotonin release action in rabbit platelet suspension. Exogenous calcium was required for its activity. Creatine phosphate/creatine phosphokinase and apyrase showed no significant inhibitory effect on aggregoserpentin-induced platelet aggregation in platelet suspension. Aggregoserpentin induced aggregation in ADP-refractory platelet-rich plasma. It caused no detectable molonic dialdehyde formation in the process of platelet aggregation. Indomethacin did not inhibit aggregoserpentin-induced platelet aggregation. Mepacrine abolished preferentially its aggregating activity, while prostaglandin E1 completely blocked both aggregoserpentine-induced aggregation and release reaction. Furthermore, platelet aggregoserpentine lowered basal and prostaglandin E1-stimulated cAMP levels in platelet suspension. Nitroprusside inhibited both its aggregating and releasing activity, while verapamil preferentially blocked its aggregating activity. It is concluded that aggregoserpentin activated platelets through lowering cAMP levels or the activation of endogenous phospholipase A2, resulting in the formation of platelet activating factor, but not of prostaglandins. 相似文献
5.
P. P. K. Ho R. D. Towner M. A. Esterman 《Preparative biochemistry & biotechnology》2013,43(5):597-613
Abstract The fatty acid cyclooxygenase (EC 1.14.99.1) that produces the prostaglandin, thromboxane, and prostacyclin precursor (PGHp), was solubilized from human platelet microsomes in 20 sucrose and 1.0% Triton X-100. The enzyme was purified 300-fold by electrofocusing, Sephadex G-200 gel filtration, and hydrophobic chromatography on ethyl agarose. The cyclooxygenase catalyzed the conversion of arachidonic acid to prostaglandin endoperioxide, PGH2, that was trapped at ?25°C and separated on TLC at ?20°C. PGH2 was hydrolyzed to HHT in acidic pH, or was chemically converted to PGE2 in slightly alkaline pH in the absence of cofactors. The enzyme showed a broad pH optimum in the range of 7–9. Hemin containing substances such as methemoglobin were absolutely required as cofactors, while tryptophan, epinephrine, phenol, and hydro-quinone stimulated the PGH2 formation. Metal ions, such as Zn2+ and Cd2+ inhibited the enzyme reaction at 0.1 to 1 mM. The molecular weight of the purified enzyme was estimated at 79,432 by sodium dodecyl sulfate disc gel electrophoresis at pH 8.0. The properties of the human platelet enzyme was generally similar to the sheep vesicular enzyme in the method of solubilization, pH optimum, and molecular weight. 相似文献
6.
Aggregation of calf platelets by platelet activating factor was characterized by a spectrophotometric method. The aggregation
kinetics of both platelet-rich plasma and purified platelets showed concave up double-reciprocal plots and linear Hill plots
withh > 1 (1.7 ± 02) consistent with positive cooperativity. Comparable values of maximum rates of aggregation(R) were obtained with platelet-rich plasma (0.25 ± 0.08) and purified platelets (0.28 ± 0.18) but the half-maximal saturation
concentration (S0.5) differed greatly between platelet-rich plasma (6 ± 3 nM) and purified platelets (0.28 ± 0.18 nM). An Arrhenius activation
energy of 21 ±2 kcal/mol was found for aggregation of purified platelets. Diltiazem was inhibitory with half-maximal inhibitory
concentration (I0.5) of 4 M but the inhibition was not competitive. Diltiazem inhibited rates but not the extent of shape-change. The receptor-antagonist
and sulphydryl reagent N-ethylmaleimide and the platelet antagonistic omega-3-fatty acid, 5,8,11,14,17-eicosa pentaenoic acid,
inhibited both rates and extent of shape-change reactions and inhibited aggregation competitively (I0.5 ∼ 5 M). Eicosa pentaenoic acid at > 25 M could abolish shape-change reactions and at 50 M served as an activator of platelets
and the activation was enhanced by aspirin (1 mM). Although N-ethylmaleimide at > 20 M could also induce platelet activation
it failed to induce aggregation and aspirin had no effect on the shape-change reactions induced by it. 相似文献
7.
Soluble materials of salivary glands fromHaemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified
to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C8 reverse phase HPLC. The purified activity, named longicomin, is a protein of molecular weight 16 000 on SDS-PAGE under both
reduced and nonreduced conditions. Collagen-mediated aggegation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effectors,
including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol-13-myristate
acetate, was observed. Longiconin had no effect on platelet adhension to collagen. Not only platelet aggregation but also
release reaction, and increase of intracellar ca2+ level of platelets in response to collagen were completely eliminated by longicomin. Increasing amounts of collagen are able
to overcome the inhibition of aggregation by longicomin, indicating that longicomin probably shares with collagen a common
receptor. In addition, collagen fibers did not emit fluorescence after incubation with isothocyanate-conjugated longicornin,
indicating that longicomin did not bind directly to collagen fibers. The identification and isolation of longicomin demonstrates
the existence of a new type of platelet inhibitor that should be useful to better undentand the mechanism of collagen stimulation
of platelets.
Project supported by the National Natural Science Foundation of China (Grant No. 39170591). 相似文献
8.
Soluble materials of salivary glands fromHaemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified
to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C8 reverse phase HPLC. The purified activity, named longicomin, is a protein of molecular weight 16 000 on SDS-PAGE under both
reduced and nonreduced conditions. Collagen-mediated aggegation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effectors,
including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol-13-myristate
acetate, was observed. Longiconin had no effect on platelet adhension to collagen. Not only platelet aggregation but also
release reaction, and increase of intracellar ca2+ level of platelets in response to collagen were completely eliminated by longicomin. Increasing amounts of collagen are able
to overcome the inhibition of aggregation by longicomin, indicating that longicomin probably shares with collagen a common
receptor. In addition, collagen fibers did not emit fluorescence after incubation with isothocyanate-conjugated longicornin,
indicating that longicomin did not bind directly to collagen fibers. The identification and isolation of longicomin demonstrates
the existence of a new type of platelet inhibitor that should be useful to better undentand the mechanism of collagen stimulation
of platelets. 相似文献
9.
Selective inhibition of prostaglandin endoperoxide thromboxane isomerase by 1-carboxyalkylimidazoles
Tanihiro Yoshimoto Shozo Yamamoto Osamu Hayaishi 《Prostaglandins & other lipid mediators》1978,16(4):529-540
1-Carboxyalkylimidazoles inhibited the conversion of prostaglandin H2 to thromboxane B2 and 12L-hydroxy-5, 8, 10- heptadecatrienoic acid by a partially purified enzyme (prostaglandin endoperoxide thromboxane isomerase) from bovine platelet microsomes. The degree of the inhibition was dependent on the length of carboxyalkyl chain. 1-Carboxyheptylimidazole was the most potent inhibitor, and an almost complete inhibition was obtained at a concentration on the order of 1 μM. The inhibition, as examined with 1-carboxyheptylimidazole, was of noncompetitive type. These 1-carboxyalkylimidazoles did not affect the formation of prostaglandin H2 from arachidonic acid. Such a selective inhibition was also demonstrated by the reaction of bovine platelet microsomes with arachidonic acid in the presence of 1-carboxyheptylimidazole, resulting in the accumulation of prostaglandin H2 as an intermediate. Furthermore, a series of 1-alkylimidazoles with no carboxyl group also inhibited the isomerase at higher concentrations. However, the inhibition was not specific for the isomerase; namely, the prostaglandin H2 formation from arachidonic acid was also affected. 相似文献
10.
Takanori Kasai Michiko Okuda Sadao Sakamura 《Bioscience, biotechnology, and biochemistry》2013,77(11):2723-2724
We found a potent platelet aggregation inhibitor in the culture broth of Streptomyces strain M-193. The inhibitor was purified as white crystals and investigated; it was identified as staurosporine. It strongly inhibited the platelet aggregation induced by collagen or ADP with IC50 values of 3.4 μm, and 11.6 μm, respectively. The inhibitor had no effect on thrombin-induced platelet aggregation or membrane stabilization against heat-induced hemolysis. 相似文献
11.
A.J. BarberR. Käser-Glanzmann M. JakábováE.F. Lüscher 《Biochimica et Biophysica Acta (BBA)/General Subjects》1972
Platelet heparin neutralizing activity (platelet factor 4) is released from human blood platelets by thrombin in the form of a high molecular weight proteoglycan-platelet factor 4 complex. This complex was partially purified by isoelectric precipitation and gel filtration. At high ionic strength (I = 0.75) the complex dissociates into the active component (mol. wt 29000) and the proteoglycan carrier. The components were separated by gel filtration and the proteoglycan further purified by Na2SO4 treatment. The molecular weight of the purified carrier was 59000. The carbohydrate moieties of the proteoglycan isolated after papain digestion and ion-echange chromatography were shown to consist of chondroitin 4-sulfate by chemical, physical and electrophoretic analysis. The multichain proteoglycan consists of four chondroitin 4-sulfate chains (mol. wt 12000) in covalent linkage to a single polypeptide. The molecular weight (350000) of the fully saturated proteoglycan carrier suggests that 4 moles of platelet factor 4 are bound per mole of proteoglycan and that the carrier occurs in the form of a dimer consisting of 8 moles of platelet factor 4 and 2 moles of proteoglycan. The isolated chondroitin 4-sulfate moieties combine with platelet factor 4 at a binding ratio of one mole of platelet factor 4 per carbohydrate chain. Heparin completely displaces platelet factor 4 from both the saturated proteoglycan and chondroitin 4-sulfate complexes. Heparitin sulfate, dermatan sulfate and chondroitin 6-sulfate also combine stoichiometrically with platelet factor 4 and are displaced by equimolar amounts of heparin. Hyaluronic acid did not combine with platelet factor 4. The relative binding capacities of glycosaminoglycans for platelet factor 4 were shown to be: heparin (100), heparitin sulfate (75), chondroitin 4-sulfate (50), dermatan sulfate (50), chondroitin 6-sulfate (50), and hyaluronic acid (o). Chondroitin 4-sulfate was identified as the major glycosaminoglycan in all platelet subcellular fractions; in addition, the soluble fraction contains a minor amount of hyaluronic acid. Subcellular distribution studies revealed that 55% of both the proteoglycan carrier and platelet factor 4 activity were localized in the “granule rich” fraction. This data together with the low recovery of both these components in the membrane fraction, suggest that they occur together as a complex within specific granules and are released in this form under physiologic conditions. 相似文献
12.
Ji-Fu Wei Xiao-long Wei Qiu-Yu Chen Tian Huang Li-Ya Qiao Wan-Yu Wang Yu-Liang Xiong Shao-Heng He 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
A novel phospholipase A2 (PLA2) with Asn at its site 49 was purified from the snake venom of Protobothrops mucrosquamatus by using SP-Sephadex C25, Superdex 75, Heparin-Sepharose (FF) and HPLC reverse-phage C18 chromatography and designated as TM-N49. It showed a molecular mass of 13.875 kDa on MALDI-TOF. TM-N49 does not possess enzymatic, hemolytic and hemorrhagic activities. It fails to induce platelet aggregation by itself, and does not inhibit the platelet aggregation induced by ADP. However, it exhibits potent myotoxic activity causing inflammatory cell infiltration, severe myoedema, myonecrosis and myolysis in the gastrocnemius muscles of BALB/c mice. Phylogenetic analysis found that that TM-N49 combined with two phospholipase A2s from Trimeresurus stejnegeri, TsR6 and CTs-R6 cluster into one group. Structural and functional analysis indicated that these phospholipase A2s are distinct from the other subgroups (D49 PLA2, S49 PLA2 and K49 PLA2) and represent a unique subgroup of snake venom group II PLA2, named N49 PLA2 subgroup. 相似文献
13.
P2Y receptors are G protein coupled receptors that respond to extracellular nucleotides to promote a multitude of signaling events. Our laboratory has purified several P2Y receptors with the goal of providing molecular insight into their: (1) ligand binding properties, (2) G protein signaling selectivities, and (3) regulation by RGS proteins and other signaling cohorts. The human P2Y1 receptor and the human P2Y12 receptor, both of which are intimately involved in ADP-mediated platelet aggregation, were purified to near homogeneity and studied in detail. After high-level expression from recombinant baculovirus infection of Sf9 insect cells, approximately 50% of the receptors were successfully extracted with digitonin. Purification of nearly homogeneous epitope-tagged P2Y receptor was achieved using metal-affinity chromatography followed by other traditional chromatographic steps. Yields of purified P2Y receptors range from 10 to 100 g/l of infected cells. Once purified, the receptors were reconstituted in model lipid vesicles along with their cognate G proteins to assess receptor function. Agonist-promoted increases in steady-state GTPase assays demonstrated the functional activity of the reconstituted purified receptor. We have utilized this reconstitution system to assess the action of various nucleotide agonists and antagonists, the relative G protein selectivity, and the influence of other proteins, such as phospholipase C, on P2Y receptor-promoted signaling. Furthermore, we have identified the RGS expression profile of platelets and have begun to assess the action of these RGS proteins in a reconstituted P2Y receptor/G protein platelet model. 相似文献
14.
An eight amino acid sequence, CAKGDWNC, from disintegrin barbourin, was introduced into an inactive human proinsulin molecule
between the B28 and A2 sites to construct a chimeric, anti-thrombosis recombinant protein. The constructed Lys-Gly-Asp (KGD)-proinsulin
gene was expressed in Escherichia coli and then purified. The KGD-proinsulin chimera protein inhibits human platelet aggregation, induced by ADP, with an IC50 value (molar concentration causing 50% inhibition of platelet aggregation) of 830 nM and demonstrates also specific affinity to glycoprotein IIb/IIIa receptor. Its insulin receptor binding activity remaines
as low as 0.04% with native insulin as a control. 相似文献
15.
Francis A. Fitzpatrick Robert R. Gorman 《Biochimica et Biophysica Acta (BBA)/General Subjects》1978,539(2):162-172
Two selective thromboxane A2 synthetase inhibitors, imidazole and 9,11-azoprosta-5,13-dienoic acid (azo analog I) were compared to determine their effects on the quantitative formation of thromboxane B2 and prostaglandin E2 accompanying human platelet aggregation. Azo analog I was at least 200 times more potent, on a molar basis, than imidazole in suppressing thromboxane B2 formation in either platelet-rich plasma or washed platelet suspensions aggregated with arachidonic acid or prostaglandin H2. The inhibitors differed in their effect on the aggregation response itself. Azo analog I selectively suppressed thromboxane A2 formation with an accompanying, parallel, suppression of the platelet aggregation.Imidazole selectively suppressed thromboxane A2 formation, but only suppressed the accompanying aggregation in platelet rich plasma, and not washed platelet suspensions. The results indicate that azo analog I functions by competitive inhibition of prostaglandin H2 on the thromboxane synthetase, and that imidazole, while it suppresses thromboxane A2 formation, may have an associated agonist activity that enhances platelet aggregation. The data presented support this hypothesis, and they emphasize the importance of thromboxane A2 in arachidonate mediated platelet aggregation. 相似文献
16.
Francis A. Fitzpatrick Robert R. Gorman 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,582(1):44-58
Thromboxane A2 plays and important role in arachidonic acid- and prostaglandin H2-induced platelet aggregation. Agents that stimulate platelet adenylate cyclase (prostaglandin I2, prostaglandin I1, and prostaglandin E1) and dibutyryl cyclic AMP inhibit both thromboxane A2 formation and arachidonate-induced aggregation platelet-rich plasma. Despite complete suppression of aggregation with agents that elevate cyclic AMP, considerable thromboxane A2 is still formed. Prostaglandin H2-induced aggregations which bypass the cyclooxygenase regulatory step are also inhibited by agents that elevate cyclic AMP without any measurable effect on thromboxane A2 production. These data demonstrate that cyclic AMP can inhibit platelet aggregation by a mechanism independent of its ability to suppress the cycyooxygenase enzyme. Parallel experiments with washed platelet preparations suggest that they may be an inadequate mode for studying relationship between the platelet cyclooxygenase and platelet function. 相似文献
17.
《Prostaglandins, Leukotrienes and Medicine》1986,21(2):157-168
Aspirin inhibits thromboxane A2 (TxA2) production whereas its salicylate moiety inhibits 12-hydroxy-eiosatetraenoic acid (12-HETE) production in the platelet. The significance of the latter effect on platelet function is unclear. We examined the effects of aspirin and salicylate on (i) platelet/ collagen adhesion using 3H-adenine-labelled human platelets and collagen- coated discs, (ii) platelet aggregation induced by thrombin, collagen, ADP and arachidonic acid, and (iii) platelet TxA2 and 12-HETE synthesis as measured by radioimmunoassay and high pressure liquid chromatography respectively. Aspirin (50 μM) decreased platelet aggregation and increased platelet adhesion. The decrease in aggregation was associated with inhibition of TxA2 production and the increase in adhesion was associated with enhanced 12-HETE production. Salicylate had the opposite effects. Platelet aggregation was increased and platelet adhesion decreased. The increased aggregation was associated with enhanced TxA2 production and the decrease in aggregation was associated with inhibition of 12-HETE production. These observations suggest that 12-HETE facilitates platelet adhesion which can be altered by salicylate treatment. 相似文献
18.
Gustavo B. Naumann Liliana F. Silva Luciana Silva Gilson Faria Michael Richardson Karla Evangelista Markus Kohlhoff Celia M.F. Gontijo Alexei Navdaev Flavia F. de Rezende Johannes A. Eble Eladio F. Sanchez 《Biochimica et Biophysica Acta (BBA)/General Subjects》2011
Background
Multifunctional l-amino acid oxidases (LAAOs) occur widely in snake venoms.Methods
The l-AAO from Bothrops leucurus (Bl-LAAO) venom was purified using a combination of molecular exclusion and ion-exchange chromatographies. We report some biochemical features of Bl-LAAO associated with its effect on platelet function and its cytotoxicity.Results
Bl-LAAO is a 60 kDa monomeric glycoprotein. Its N-terminal sequence shows high homology to other members of the snake-venom LAAO family. Bl-LAAO catalyzes oxidative deamination of l-amino acids with the generation of H2O2. The best substrates were: l-Met, l-Norleu, l-Leu, l-Phe and l-Trp. The effects of snake venom LAAOs in hemostasis, especially their action on platelet function remain largely unknown. Bl-LAAO dose-dependently inhibited platelet aggregation of both human PRP and washed platelets. Moreover, the purified enzyme exhibited a killing effect in vitro against Leishmania sp., promastigotes, with a very low EC50 of 0.07 μM. Furthermore, the cytotoxicity of Bl-LAAO was observed in the stomach cancer MKN-45, adeno carcinoma HUTU, colorectal RKO and human fibroblast LL-24 cell lines. The enzyme released enough H2O2 in culture medium to induce apoptosis in cells in a dose- and time-dependent manner. The biological effects were inhibited by catalase.Conclusion
Bl-LAAO, a major component of B. leucurus venom, is a cytotoxin acting primarily via the generation of high amounts of H2O2 which kill the cells.General significance
These results allow us to consider the use of LAAOs as anticancer agents, as tools in biochemical studies to investigate cellular processes, and to obtain a better understanding of the envenomation mechanism. 相似文献19.
Stewart A. Lonky James Marsh Herbert Wohl 《Biochemical and biophysical research communications》1978,85(3):1113-1118
Highly purified platelet factor 4 (PF4) was found to be a potent stimulator of human granulocyte elastase activity against native elastin and solubilized α elastin. Heparin neutralized this stimulation of elastolysis by PF4, but independently stimulated granulocyte elastase activity. Chondroitin sulfate, a constituent of the PF4 carrier molecule, also stimulated granulocyte elastase activity. The stimulation of granulocyte elastase by PF4 occurs at known serum concentrations of PF4. 相似文献
20.
Il Kwon Sung-Yu Hong Young Dae Kim Hyo Suk Nam Sungsoo Kang Seung-Hee Yang Ji Hoe Heo 《PloS one》2013,8(11)
Saxatilin, a novel disintegrin purified and cloned from the venom of the Korean snake Gloydius saxatilis, strongly inhibits activation and aggregation of platelets. Glycoprotein (GP) IIb/IIIa receptor antagonists can resolve thrombus, so saxatilin might also have thrombolytic effects. We investigated the thrombolytic effects of saxatilin in mice using a ferric chloride-induced carotid arterial thrombosis model. Thrombotic occlusion and thrombus resolution were evaluated quantitatively by measuring blood flow in the carotid artery with an ultrasonic flow meter and calculating the degree of flow restoration on a minute-by-minute basis; results were confirmed by histological examination. Saxatilin dissolved thrombi in a dose-dependent manner. Saxatilin at 5 mg/kg restored blood flow to baseline levels. As saxatilin dose increased, time to recanalization decreased. A bolus injection of 10% of a complete dose with continuous infusion of the remaining dose for 60 minutes resulted in effective recanalization without reocclusion. The thrombolytic effect of saxatilin was also demonstrated in vitro using platelet aggregometry by administering saxatilin in preformed thrombi. Bleeding complications were observed in 2 of 71 mice that received saxatilin. Fibrin/fibrinogen zymography and platelet aggregometry studies indicated that saxatilin does not have fibrinolytic activity, but exerted its action on platelets. Integrin-binding assays showed that saxatilin inhibited multiple integrins, specifically α2bβ3 (GP IIb/IIIa), α5β1, αvβ3, αvβ1, and αvβ5, which act on platelet adhesion/aggregation. Saxatilin inhibited multiple integrins by acting on platelets, and was safe and effective in resolving thrombi in mice. 相似文献