939 resultados para Estradiol -- pharmacology
Resumo:
A novel bombesin-related peptide was isolated from skin secretions of Chinese red belly toad Bombina maxima. Its primary structure was established as pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH2. The amino-terminal (N-terminal) 8-residue segment comprising four prolines and three basic residues is extensively different from bombesins from other Bombina species. The peptide was thus named proline rich bombesin (PR-bombesin). PR-bumbesin was found to elicit concentration-dependent contractile effects in the rat stomach strip, with both increased potency and intrinsic activity as compared with those of [Leu(13)]bombesin. Analysis of different bombesin cDNA structures revealed that an 8 to 14- nucleotide fragment replacement in the peptide coding region (TGGGGAAT in the cDNAs of multiple bombesin forms from Bombina orientalis and CACCCCGGCCACCC in the cDNA of PR-bombesin) resulted in an unusual Pro-Pro-Arg-Pro-Pro motif in the N-terminal part of PR-bombesin. (C) 2002 Elsevier Science Inc. All rights reserved.
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An opioid peptide, which shares similarity with mammalian hemorphins, has been identified from the synganglia (central nervous system) of the hard tick, Amblyomma testindiarium. Its primary sequence was established as LVVYPWTKM that contains a tetrapeptide sequence Tyr-Pro-Trp-Thr of hemorphin-like opioid peptides. By hot-plate bioassay, the purified peptide and synthetic peptide displayed dose-related antinociceptive effect in mice, as observed for other hemorphin-like opioid peptides. This is the first opioid peptide identified from ticks. Ticks may utilize the opioid peptide in their strategy to escape host immuno-surveillance as well as in inhibiting responses directed against themselves. (c) 2004 Elsevier Inc. All rights reserved.
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Rong Gao, Yun Zhang, Qing-Xiong Meng, Wen-Hui Lee, Dong-Sheng Li, Yu-liang Xiong and Wan-Yu Wang. Characterization of three fibrinogenolytic enzymes from Chinese green tree viper (Trimeresurus stejneger ) venom. Toxicon 36, 457-467, 1998.-From the venom of Chinese green tree viper (Trimeresurus stejnegeri), three distinct fibrinogenolytic enzymes: stejnefibrase-l, stejnefibrase-2 and stejnefibrase-3, were purified by gel filtration, ion-exchange chromatography and reverse-phase high-performance chromatograghy (HPLC). SDS-PAGE analysis of those three enzymes showed that they consisted of a single polypeptide chain with mel. wt of -50 000, 31 000 and 32 000, respectively. Like TSV-PA (a specific plasminogen activator) and stejnobin (a fibrinogen-clotting enzyme) purified from the same venom, stejnfibrase-1, -2 and -3 were able to hydrolyze several chromogenic substrate. On the other hand, different from TSV-PA. and stejnobin, stejnefibrase-l, -2 and -3 did not activate plasminogen and did not possess fibrinogen-clotting activity. The three purified enzymes directly degraded fibrinogen to small fragments and rendered it unclottable by thrombin. Stejnefibrase-2 degraded preferentially BE-chain while stejnefibrase-l and -3 cleaved concomitantly Ax and B beta-chains of fibrinogen. None of these proteases degraded the gamma-chain of fibrinogen. When correlated with the loss of clottability of fibrinogen, the most active enzyme was stejnefibrase-l. The activities of the three enzymes were inhibited by phenylmethylsulfonyl fluoride (PMSF) and p-nitrophenyl-p-guanidinobenzoate (NPGB), indicating that like TSV-PA and stejnobin, they are venom serine proteases. (C) 1998 Elsevier Science Ltd. All rights reserved.
Resumo:
Trimeresurus stejnegeri venom, which contains TSV-PA (a specific plasminogen activator sharing 60-70% sequence homology with venom fibrinogen-clotting enzymes), also possesses fibrinogen-clotting activity in vitro. A fibrinogen-clotting enzyme (stejnobin) has been purified to homogeneity by gel filtration and ion-exchange chromatography on a Mono-Q column. It is a single-chain glycoprotein with a mol. wt of 44,000. The NH2-terminal amino acid sequence of stejnobin shows great homology with venom fibrinogen-clotting enzymes and TSV-PA. Like TSV-PA, stejnobin was able to hydrolyse several chromogenic substrates. Comparative study of substrate specificities of stejnobin and other venom proteases purified in our laboratory was carried out on five chromogenic substrates. Stejnobin clotted human fibrinogen with a specific activity of 122 NIH thrombin-equivalent units/mg protein. However, stejnobin did not act on other blood coagulation factors, such as factor X, prothrombin and plasminogen. Diisopropyl fluorophosphate and phenylmethanesulfonyl fluoride inhibited its activity, whereas ethylenediamine tetracetic acid had no effect on it, indicating that it is a serine protease. Although stejnobin showed strong immunological cross-reaction with polyclonal antibodies raised against TSV-PA, it was interesting to observe that, unlike the case of TSV-PA, these antibodies did not inhibit the amidolytic and fibrinogen-clotting activities of stejnobin. (C) 1998 Elsevier Science Ltd. All rights reserved.
Resumo:
The action of Pallas' viper (Agkistrodon halys pallas) venom on blood coagulation was examined in vitro and a strong anticoagulant effect was observed. This action was abolished after treatment with a specific inhibitor of phospholipase A(2) activity (p-bromophenacyl bromide), revealing a procoagulant action in low concentrations of treated venom (around 1 mu g/ml). The effect of the venom an haemostasis was further characterized by measuring its ability to activate purified blood coagulation factors. It is concluded that A. halys pallas venom contains prothrombin activation activity. A prothrombin activator (aharin) was purified from the venom by Sephadex G-75 gel filtration and ion-exchange chromatography on a Mono-Q column. It consisted of a single polypeptide chain, with a mol. wt of 63,000. Purified aharin possessed no amidolytic activity on chromogenic substrates. It did not act on other blood coagulation factors, such as factor X and plasminogen, nor did it cleave or clot purified fibrinogen. The prothrombin activation activity of aharin was readily inhibited by ethylenediamine tetracetic acid (a metal chelator), but specific serine protease inhibitors such as diisopropyl fluorophosphate and phenylmethanesulfonyl fluoride had no effect on it. These observations suggest that, like those prothrombin activators from Echis carinatus and Bothrops atrox venoms, the prothrombin activator from A. halys pallas venom is a metalloproteinase. (C) 1998 Elsevier Science Ltd. All rights reserved.
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Mastoparans are a family of small peptides identified from the venom of hymenopteroid insects. Although they have been characterized as early as 1979, and so far are recognized as a leading biomolecule in potential drug therapy, their precursors, mastopar
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There are around 27 species of Amolops amphibian distributed in South-east of Asia. Seven antimicrobial peptides (AMPs) belonging to two different families were purified from skin of rufous-spotted torrent frog, Amolops loloensis, and designated brevinins
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A number of C-type lectins with various biological activities have been purified and characterized from Viperidae snake venoms. In contrast, only a few reports could be found in literature concerning the C-type lectins in Elapidae snake venoms. Based on t
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Two antimicrobial peptides manifested a broad spectrum of anti microbial activity against various microorganisms have been isolated from skin secretions of Rana grahami. These antimicrobial peptides were named grahamin 1 and grahamin 2. Their primary Stru
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PR-bombesin is a bombesin-like peptide derived from the skin of tile Chinese red belly toad, Bombina maxima. The 8-residue segment of N-terminal of RP-bombesin, comprising four prolines and three basic residues, is extensively different front other bombes
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The hornet possesses highly toxic venom, which is rich in toxin, enzymes and biologically active peptides. Many bioactive substances were identified from wasp venom. Two families of antimicrobial peptides were purified and characterized from the venom of
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A novel antimicrobial peptide named as ixosin was isolated from the salivary glands of the hard tick, Ixodes sinensis, by gel filtration, ion exchange chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC). Its amino acid sequen
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A blood coagulation factor IX-binding protein (TSV-FIX-BP) was isolated from the snake venom of Trimeresurus stejnegeri. On SDS-polyacrylamide gel electrophoresis, TSV-FIX-BP showed a single band with an apparent molecular weight of 23,000 under non-reducing conditions. and two distinct bands with apparent molecular weights of 14,800 and 14,000 under reducing conditions. cDNA clones containing the coding sequences of TSV-FIX-BP were isolated and sequenced to determine the structure of the precusors of TSV-FIX-BP subunits. The deduced amino acid sequences of two subunits of TSV-FIX-BP were confirmed by N-terminal protein sequencing and trypsin-digested peptide mass fingerprinting. TSV-FIX-BP was a nonenzymatic C-type lectin-like anti-coagulant. The anti-coagulant activity of TSV-FIX-BP was mainly caused by its dose dependent interaction with blood coagulation factor IX but not with blood coagulation factor X. (C) 2003 Elsevier Science Ltd. All rights reserved.
Resumo:
A platelet glycoprotein Ib-binding protein, termed TSV-GPIb-BP, was isolated from the venom of Trimeresurus stejnegeri. On SDS-polyacrylamide gel electrophoresis, TSV-GPIb-BP showed a single band with an apparent molecular weight of 28,000 and two distinct bands with apparent molecular weights of 16,000 and 15,000 under non-reducing and reducing conditions, respectively. cDNA clones containing the coding sequences for both TSV-GPIb-BP subunits were isolated and sequenced. The deduced amino acid sequences of TSV-GPIb-BP subunits were confirmed by N-terminal protein sequencing and trypsin-digested peptide mass fingerprinting. Interestingly, the a subunit of TSV-GPIb-BP is identical to that of alboaggregin-B, and the sequence identity of their beta subunits is 94.3%. TSV-GPIb-BP inhibited ristocetin-induced human platelet agglutination in platelet-rich plasma under lower dosages (<5 mug/ml). On the other hand, it directly aggregated washed human platelets in the absence of additional Ca2+ or any other cofactors under higher dosages (>5 mug/ml). This platelet aggregation activity was dose-dependently inhibited by specific GPIbalpha antibodies, but not by those antibodies against platelet GPIa, GPIIa, GPIIb and GPIIIa. (C) 2003 Elsevier Science Ltd. All rights reserved.
Resumo:
A novel 28-amino acid peptide, termed bombinakinin-GAP, was purified and characterized from skin secretions of the toad Bombina maxima. Its primary structure was established as DMYEIKQYKTAHGRPPICAPGEQCPIWV-NH2, in which two cysteines form a disulfide bond. A FASTA search of SWISS-PROT databank detected a 32% sequence identity between the sequences of the peptide and a segment of rat cocaine- and amphetamine-regulated transcript (CART). Intracerebroventricular (i.c.v.) administration of the peptide induced a significant decrease in food intake in rats, suggesting that it played a role in the control of feeding by brain. Analysis of its cDNA structure revealed that this peptide is coexpressed with bombinakinin M, a bradykinin-related peptide from the same toad. Bombinakinin-GAP appears to be the first example of a novel class of bioactive peptides from amphibian skin, which may be implicated in feeding behavior. (C) 2003 Elsevier Science Inc. All rights reserved.