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The cleavage sequence of fibrinopeptide A from fibrinogen fragment E by thrombin, atroxin or batroxobin.

Calculations of data from fibrin polymerization and cross-linking experiments infer that thrombin-catalysed release of the second of the two fibrinopeptides A (FpA2) from fibrinogen is concerted, although other data suggest that FpA2 release is random. In the concerted pattern of FpA release, divalent monomer (des AA-fibrin) formation predominates throughout the enzymatic conversion of fibrinogen to fibrin, an effect leading to relatively rapid fibril assembly. Alternatively, random FpA2 release would result in a substantial population of monovalent monomer (des A-fibrin) intermediates during early and intermediate phases of the enzymatic conversion to fibrin. Their formation would cause a delay in fibrin fibril assembly. In order to address the question of the pattern of FpA release directly, we purified plasmic fibrinogen fragment E1 isoforms containing both FpA sequences and studied the sequence of FpA release by thrombin or batroxobin. Des A-fragment E1 intermediates formed by loss of one FpA (FpA1), and des AA-fragment E1 products (lacking both FpA1 and FpA2) were identified by analytical isoelectric focusing and quantified by densitometry. The catalytic rate of release of FpA1 (k1) and FpA2 (k2) by thrombin or batroxobin was similar. The ratio of these rates, k2:k1, was 1.10 +/- 0.42 for thrombin and 1.34 +/- 0.26 for batroxobin. These findings indicate that these enzymes cleave FpA2 randomly from fragment E1.

Batroxobin

Novel structure of the N-acetylgalactosamine containing N-glycosidic carbohydrate chain of batroxobin, a thrombin-like snake venom enzyme.

The structure of the Asn-linked carbohydrate chain of batroxobin, a thrombin-like enzyme from Bothrops atrox moojeni snake venom, has been determined. The sugar chain was isolated from batroxobin by hydrazinolysis followed by pyridylamination (PA). The PA-oligosaccharide chain was purified by HPLC on an anion exchange or reverse phase columns, and its structure was examined by sequential exoglycosidase digestion, 600 MHZ 1H NMR spectroscopy and methylation analysis. The results indicate that the oligosaccharide chain has the following structure involving a novel linkage, NeuAc alpha 2----3GalNAc.

Acetylgalactosamine

Metabolic fate of 125I-labeled batroxobin in rats and dogs.

125I-Labeled batroxobin was prepared and following its intravenous and subcutaneous administrations to rats and dogs, the blood radioactivity was determined. In the both species following the intravenous injections, the decrease in radioactivity was biexponential. Following subcutaneous administration, radioactivity became maximal at 6h and decreased in a manner similar to that of the beta-phase of the intravenous injection. The blood concentration of fibrinogen in dogs was also determined. After the intravenous injection, fibrinogen became undetectable 1h later, and appeared again in the blood at 24h. After the subcutaneous injection, the decrease was not so rapid. Fibrinogen resumed its original levels at 7 day after the administration in both the routes. Radioactivity after the both injections was excreted generally in the urine in about the same amounts. The total urinary and fecal excretions in rats and dogs were 80 and 95%, respectively. The distribution of radioactivity in the tissues was examined by counting technique and whole-body autoradiography. Radioactivity predominantly accumulated in the thyroid and stomach and could also be found in the kidneys and liver in fair amounts. The distribution patterns of radioactivity for both the routes of administrations and also for male and pregnant rats were basically the same. In fetus rats, a slight distribution was noted. From the results of gel filtration chromatography and trichloroacetic acid fractionation, [125I] batroxobin was metabolized soon after the administration to afford low molecular substances such as 125I-ion in the plasma and urine.

Animals

[The use of Soviet substitutes for batroxobin in the determination of fibrinogen].

Plasma fibrinogen was measured by kinetic photometry with two Soviet analogs of the foreign agent batroxobin: ancistron-N and agichal, obtained from Central Asian Aspidelaps lubricus venom by different techniques. Both the preparations of thrombin-like enzyme from the venom have proved to be adequate substituents of batroxobin; the optimal concentration of ancistron-N for this test was found to be 20 micrograms/ml or 0.04 U/ml, that of agichal 0.5 micrograms/ml.

Fibrinogen

The activation of plasma factor XIII with the snake venom enzymes ancrod and batroxobin marajoensis.

The snake venom enzymes Ancrod and Batroxobin marajoensis are able to activate human plasma factor XIII as shown by the formation of the gamma-dimers. The concentration of gamma-dimers increases with the concentration of the activating enzymes. Factor XIII activated by Ancrod or Batroxobin marajoensis is, however, unable to catalyse the incorporation of the amine dansyl-cadaverine into casein. The partially activated factor XIII is therefore not demonstrable by means of the artificial test system. This factor XIII loses little activity and remains activable by thrombin.

Ancrod

Release of plasminogen activator by batroxobin.

In the isolated perfused pig ear, batroxobin caused a dose-dependent increase in the release of plasminogen activator. The activator-releasing effect required the presence of the active enzyme. The activator released was of the tissue-type.

Animals

The effect of batroxobin on cochlear blood flow.

Cochlear blood flow is considered to be closely related to cochlear function. Among several etiologic factors implicated in inner ear diseases, disturbance of local blood flow is held to be one of the most important. With this in view, various pharmaceuticals are currently being used to increase local blood flow in patients with inner ear diseases. In the control of blood flow there are three major factors; systemic blood pressure (perfusion pressure), vascular tone, and blood viscosity. Batroxobin (BX) was developed to increase local blood flow by lowering blood viscosity through defibrinogenation; it is used in the treatment of thrombosis and occasionally for the treatment of sudden deafness. In the present study, we observed the effect of BX on cochlear blood flow in guinea pigs, using a laser Doppler flowmeter, and measured the blood fibrinogen concentration after BX infusion. There was an obvious increase in cochlear blood flow during the observation period of 3 h after 10 BU/kg were infused, and a slight increase when 2 BU/kg were infused. Blood fibrinogen levels decreased dramatically by 30 min after BX infusion (10 BU/kg), and the extremely low level attained was maintained throughout the 3-h observation period. Hemorrhage from the surgically opened ear was noted in 2 animals during the experiment and rectal bleeding in one.

Animals

[Kinetic fibrinogen determination with batroxobin (reptilase)].

A kinetic turbidity-producing method for fibrinogen determination on the basis of reptilase reagent (batroxobin) is described. The method, which is in good agreement with method by Clauss shows comparable precision, is marked out by the possibility of objective photometric measurement. Reagent stability, use of undiluted test plasma and single-point calibration are further advantages. The method is insensitive to heparin. With regards to FDP it is less disturbed than the method by Clauss. In case of adaptation to a modern photometer a clear rationalization effect can be achieved.

Batroxobin

Comparison of the actions of thrombin and the thrombin-like venom enzymes ancrod and batroxobin.

Thrombin acts on several coagulant proteins to produce products with physiologic, pharmacologic and pathologic potential. The most sensitive thrombin substrate seems to be factor VIII. Some thrombin dependent reactions studied in vitro and proposed as control reactions seem too insensitive to the action of thrombin to be of in vivo significance. The only enzymic reaction the thrombin-like venom enzymes, Ancrod and Batroxobin, have in common with thrombin is the removal of fibrinopeptide A.

Ancrod