RESUMO
Bradykinin (BK) is a peptide hormone that plays a crucial role in blood pressure control, regulates inflammation in the human body, and has recently been implicated in the pathophysiology of COVID-19. In this study, we report a strategy for fabricating highly ordered 1D nanostructures of BK using DNA fragments as a template for self-assembly. We have combined synchrotron small-angle X-ray scattering and high-resolution microscopy to provide insights into the nanoscale structure of BK-DNA complexes, unveiling the formation of ordered nanofibrils. Fluorescence assays hint that BK is more efficient at displacing minor-groove binders in comparison with base-intercalant dyes, thus, suggesting that interaction with DNA strands is mediated by electrostatic attraction between cationic groups at BK and the high negative electron density of minor-grooves. Our data also revealed an intriguing finding that BK-DNA complexes can induce a limited uptake of nucleotides by HEK-293t cells, which is a feature that has not been previously reported for BK. Moreover, we observed that the complexes retained the native bioactivity of BK, including the ability to modulate Ca2+ response into endothelial HUVEC cells. Overall, the findings presented here demonstrate a promising strategy for the fabrication of fibrillar structures of BK using DNA as a template, which keep bioactivity features of the native peptide and may have implications in the development of nanotherapeutics for hypertension and related disorders.
Assuntos
Bradicinina , COVID-19 , Humanos , Bradicinina/química , Bradicinina/farmacologia , Peptídeos , Transdução de Sinais , Células EndoteliaisRESUMO
Bradykinin-potentiating peptides (BPPs) are an important group of toxins present in Lachesis muta rhombeata venom. They act directly at renin-angiotensin-aldosterone system, through the inhibition of angiotensin-converting enzyme (ACE). This action may contribute to the hypotensive shock observed during the envenoming by this species. Thus, the main goal of this study was the solid-phase synthesis of a BPP found in L. m. rhombeata venom and its in vitro and in vivo characterization in relation to ACE inhibition and hypotensive activity, respectively. The LmrBPP9 peptide was synthesized using an automated solid-phase peptide synthesizer and purified by reversed-phase fast protein liquid chromatography (FPLC). The in vitro IC50 of the synthetic peptide is 4.25⯱â¯0.10⯵M, showing a great capacity of ACE inhibition. The in vivo studies showed that LmrBPP9 induces blood pressure reduction, both in normotensive and hypertensive rats, being more pronounced in the last ones. These results agree with the in vitro results, showing that the synthetic peptide LmrBPP9 is a potential molecule to the development of a new antihypertensive drug.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/síntese química , Anti-Hipertensivos/síntese química , Hipotensão/tratamento farmacológico , Peptídeos/síntese química , Inibidores da Enzima Conversora de Angiotensina/administração & dosagem , Inibidores da Enzima Conversora de Angiotensina/química , Animais , Anti-Hipertensivos/administração & dosagem , Anti-Hipertensivos/química , Bradicinina/química , Venenos de Crotalídeos/química , Peptídeos/administração & dosagem , Peptídeos/química , Peptidil Dipeptidase A/química , Ratos , Sistema Renina-Angiotensina/efeitos dos fármacos , Venenos de Serpentes/química , ViperidaeRESUMO
This study uses EPR, CD, and fluorescence spectroscopy to examine the structure of bradykinin (BK) analogues attaching the paramagnetic amino acid-type Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at positions 0, 3, 7, and 9. The data were correlated with the potencies in muscle contractile experiments and the substrate properties towards the angiotensin I-converting enzyme (ACE). A study of the biological activities in guinea pig ileum and rat uterus indicated that only Toac0-BK partially maintained its native biological potency among the tested peptides. This and its counterpart, Toac3-BK, maintained the ability to act as ACE substrates. These results indicate that peptides bearing Toac probe far from the ACE cleavage sites were more susceptible to hydrolysis by ACE. The results also emphasize the existence of a finer control for BK-receptor interaction than for BK binding at the catalytic site of this metallodipetidase. The kinetic kcat/Km values decreased from 202.7 to 38.9µM-1min-1 for BK and Toac3-BK, respectively. EPR, CD, and fluorescence experiments reveal a direct relationship between the structure and activity of these paramagnetic peptides. In contrast to the turn-folded structures of the Toac-internally labeled peptides, more extended conformations were displayed by N- or C-terminally Toac-labeled analogues. Lastly, this work supports the feasibility of monitoring the progress of the ACE-hydrolytic process of Toac-attached peptides by examining time-dependent EPR spectral variations.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/farmacologia , Bradicinina/farmacologia , Íleo/efeitos dos fármacos , Peptidil Dipeptidase A/metabolismo , Útero/efeitos dos fármacos , Inibidores da Enzima Conversora de Angiotensina/síntese química , Inibidores da Enzima Conversora de Angiotensina/química , Animais , Bradicinina/síntese química , Bradicinina/química , Relação Dose-Resposta a Droga , Feminino , Cobaias , Íleo/metabolismo , Conformação Molecular , Ratos , Relação Estrutura-Atividade , Útero/metabolismoRESUMO
RATIONALE: The increased use of silver nanoparticles (AgNPs) for various biological applications, and over-expression of various peptide receptors in different tumors/cancer cells, necessitate the need for dedicated investigations on the intrinsic binding ability of Ag with various biologically important peptides for better understanding of AgNPs-peptide interactions and for the future development of contrasting agents as well as drugs for imaging/biomedical applications. METHODS: The [M+(Ag)n ](+) complexes are prepared and characterized using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). RESULTS: Silver complexes of the peptides [M+(Ag)n ](+) , where M = oxytocin, arg(8) -vasopressin, bradykinin, bombesin, somatostatin, and neurotensin, have been investigated for their intrinsic Ag(+) -binding ability. Unusual binding of up to seven Ag(+) with these small peptides is observed. The mass spectra show n = 1-5 for bombesin and somatostatin, n = 1-6 for bradykinin and arg(8) -vasopressin, and n = 1-7 for oxytocin and neurotensin. In addition, oxytocin and arg(8) -vasopressin show the formation of dimers and their complexes [M2 +(Ag)n ](+) with n = 1-8 and n = 1-5, respectively. The possible amino acid residues responsible for Ag(+) binding in each peptide have been identified on the basis of density functional theory (DFT)-calculated binding energy values of Ag(+) towards individual amino acids. CONCLUSIONS: Mass spectrometric evidence indicates that the peptides, viz., oxytocin, arg(8) -vasopressin, bradykinin, bombesin, somatostatin, and neurotensin, show greater affinity for Ag(+) . Hence, they may be used as carriers for AgNPs in targeted drug delivery as well as an alternative for iodinated contrasting agents in dual energy X-ray imaging techniques. Radio-labeled Ag with these peptides can also be used in radio-pharmaceuticals for diagnostic and therapeutic applications. Copyright © 2016 John Wiley & Sons, Ltd.
Assuntos
Peptídeos/química , Prata/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Sequência de Aminoácidos , Sítios de Ligação , Bombesina/química , Bradicinina/química , Nanopartículas Metálicas/química , Modelos Moleculares , Neurotensina/química , Ocitocina/química , Somatostatina/química , Vasopressinas/químicaRESUMO
To find effective new candidate antimalarial drugs, bradykinin and its analogs were synthesized and tested for effectiveness against Plasmodium gallinaceum sporozoites and Plasmodium falciparum on erythrocytes. Among them, bradykinin and its P2 analog presented high activity against Plasmodium gallinaceum, but they degrade in plasma. On the other hand, RI-BbKI did not degrade and reached high activity. No analog was active against Plasmodium falciparum.
Assuntos
Antimaláricos/farmacologia , Bradicinina/farmacologia , Peptídeos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium gallinaceum/efeitos dos fármacos , Animais , Antimaláricos/síntese química , Antimaláricos/química , Bradicinina/química , Bradicinina/genética , Humanos , Peptídeos/síntese química , Peptídeos/química , Peptídeos/genética , Esporozoítos/efeitos dos fármacosRESUMO
In a recent work by our group involving a transcriptomics approach applied to the venom glands from Tityus stigmurus we identified a new family of peptides called Hypotensins (TSTI0006C) (Almeida et al., 2012). The cluster TSTI0006C was analyzed in the main 25 amino acid residues and named T. stigmurus Hypotensin (TistH), showing a molecular mass of 2.7 kDa, an absence of cysteines and the presence of two C-terminal proline residues, which are a bradykinin-potentiating peptide (BPP) signature. Here, we describe the homology modeling of the three-dimensional structure of TistH. In addition, we evaluated the cardiovascular effects elicited by TistH in normotensive rats. Firstly, TistH showed no cytotoxic effect on horse erythrocyte. Furthermore, in normotensive rats TistH was able to potentiate the hypotensive action of bradykinin (BK) and induced a vasorelaxant effect in mesenteric artery rings by endothelium-dependent release of nitric oxide (NO) and demonstrated independent inhibition of angiotensin converting enzyme (ACE). Our data can contribute to a better understanding of the structural and functional characteristics of TistH and suggest its potential use in cardiovascular diseases.
Assuntos
Bradicinina/farmacologia , Venenos de Escorpião/farmacologia , Escorpiões/metabolismo , Vasodilatadores/farmacologia , Inibidores da Enzima Conversora de Angiotensina/química , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Animais , Anti-Hipertensivos/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Bradicinina/química , Sistema Cardiovascular/efeitos dos fármacos , Sistema Cardiovascular/metabolismo , Clonagem Molecular , Biologia Computacional , Modelos Moleculares , Óxido Nítrico/metabolismo , Peptidil Dipeptidase A/metabolismo , Ratos , Ratos Wistar , Venenos de Escorpião/química , Transcriptoma , Vasodilatadores/químicaRESUMO
Bradykinin-potentiating peptides from Bothrops jararaca (Bj) discovered in the early 1960s, were the first natural inhibitors of the angiotensin-converting enzyme (ACE). These peptides belong to a large family of snake venom proline-rich oligopeptides (PROs). One of these peptides, Bj-PRO-9a, was essential for defining ACE as effective drug target and development of captopril, an active site-directed inhibitor of ACE used worldwide for the treatment of human arterial hypertension. Recent experimental evidences demonstrated that cardiovascular effects exerted by different Bj-PROs are due to distinct mechanisms besides of ACE inhibition. In the present work, we have investigated the cardiovascular actions of four Bj-PROs, namely Bj-PRO-9a, -11e, -12b and -13a. Bj-PRO-9a acts upon ACE and BK activities to promote blood pressure reduction. Although the others Bj-PROs are also able to inhibit the ACE activity and to potentiate the BK effects, our results indicate that antihypertensive effect evoked by them involve new mechanisms. Bj-PRO-11e and Bj-PRO-12b involves induction of [Ca(2+)]i transients by so far unknown receptor proteins. Moreover, we have suggested argininosuccinate synthetase and M3 muscarinic receptor as targets for cardiovascular effects elicited by Bj-PRO-13a. In summary, the herein reported results provide evidence that Bj-PRO-mediated effects are not restricted to ACE inhibition or potentiation of BK-induced effects and suggest different actions for each peptide for promoting arterial pressure reduction. The present study reveals the complexity of the effects exerted by Bj-PROs for cardiovascular control, opening avenues for the better understanding of blood pressure regulation and for the development of novel therapeutic approaches.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/administração & dosagem , Anti-Hipertensivos/metabolismo , Hipertensão/patologia , Oligopeptídeos/administração & dosagem , Peptidil Dipeptidase A/metabolismo , Inibidores da Enzima Conversora de Angiotensina/metabolismo , Animais , Anti-Hipertensivos/administração & dosagem , Anti-Hipertensivos/química , Bothrops/metabolismo , Bradicinina/química , Bradicinina/uso terapêutico , Humanos , Hipertensão/tratamento farmacológico , Peptidil Dipeptidase A/química , Domínios Proteicos Ricos em Prolina , Venenos de Serpentes/químicaRESUMO
The subfamily Phyllomedusinae has attracted a great interest of many researchers mainly due to the high diversity of these frog species and plethora of pharmacological activities frequently observed for their skin secretions. Despite of this fact, mainly for new species, limited information is available regarding the molecular composition of these skin secretions and the cellular components involved in their production. Phyllomedusa nordestina is a recently described Brazilian frog species also popularly known as 'tree-frogs'. Aiming at contributing to the biological knowledge of this species, we show here the gene expression profile of this frog skin secretion using a global ESTs analysis of a cDNA library. The marked aspect of this analysis revealed a significant higher transcriptional level of the opioid peptide dermorphins in P. nordestina skin secretion than in Phyllomedusa hypochondrialis, which is its closest related species, belonging both to the same phylogenetic group. Precursors of bioactive peptides as dermaseptins, phylloseptins, tryptophyllins, and bradykinin-like peptideswere also found in this library. Transcripts encoding proteins related to ordinary cellular functions and pathways were also described. Some of them are chiefly involved in the production of the skin secretion. Taken together, the data reported here constitute a contribution to the characterization of the molecular diversity of gene-encoded polypeptides with potential possibility of pharmacological exploitation. The transcriptional composition of the skin secretion may also help to give the necessary support for the definition of P. nordestina as a new species, which actually relies basically on frog morphological characteristics and geographical distribution.
Assuntos
Anuros/fisiologia , Glândulas Exócrinas/química , Etiquetas de Sequências Expressas/química , Pele/química , Sequência de Aminoácidos , Proteínas de Anfíbios/química , Animais , Peptídeos Catiônicos Antimicrobianos/química , Bradicinina/química , Brasil , DNA Complementar/biossíntese , DNA Complementar/genética , Glândulas Exócrinas/metabolismo , Expressão Gênica/fisiologia , Biblioteca Gênica , Cininogênios/química , Dados de Sequência Molecular , Oligopeptídeos/química , Peptídeos Opioides/química , Peptídeos/química , Pele/metabolismo , Especificidade da EspécieRESUMO
Cellular membranes have relevant roles in processes related to proteases like human kallikreins and cathepsins. As enzyme and substrate may interact with cell membranes and associated co-factors, it is important to take into account the behavior of peptide substrates in the lipid environment. In this paper we report an study based on energy transfer in two bradykinin derived peptides labeled with the donor-acceptor pair Abz/Eddnp (ortho-aminobenzoic acid/N-[2,4-dinitrophenyl]-ethylenediamine). Time-resolved fluorescence experiments were performed in phosphate buffer and in the presence of large unilamelar vesicles of phospholipids, and of micelles of sodium dodecyl sulphate (SDS). The decay kinetics were analyzed using the program CONTIN to obtain end-to-end distance distribution functions f(r). Despite of the large difference in the number of residues the end-to-end distance of the longer peptide (9 amino acid residues) is only 20 % larger than the values obtained for the shorter peptide (5 amino acid residues). The proline residue, in position 4 of the bradykinin sequence promotes a turn in the longer peptide chain, shortening its end-to-end distance. The surfactant SDS has a strong disorganizing effect, substantially broadening the distance distributions, while temperature increase has mild effects in the flexibility of the chains, causing small increase in the distribution width. The interaction with phospholipid vesicles stabilizes more compact conformations, decreasing end-to-end distances in the peptides. Anisotropy experiments showed that rotational diffusion was not severely affected by the interaction with the vesicles, suggesting a location for the peptides in the surface region of the bilayer, a result consistent with small effect of lipid phase transition on the peptides conformations.
Assuntos
Bradicinina/química , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Fosfolipídeos/metabolismo , Lipossomas Unilamelares/metabolismo , Sequência de Aminoácidos , Dimiristoilfosfatidilcolina/metabolismo , Cinética , Micelas , Fosfatidilgliceróis/metabolismo , Ligação Proteica , Espectrometria de Fluorescência , Água/químicaRESUMO
The effects of lipopolysaccharide (LPS) and desArg9Bradykinin (DBK) on the release of nitric oxide (NO) from macrophages of mice 8, 12 and 18 days after having been treated with low doses of streptozotocin (STZ; 5 × 45 mg/kg) were studied. The results showed that LPS stimulated the release of NO from macrophages of untreated animals by 50% whereas the bradykinin B(1) agonist desArg9Bradykinin (DBK) increased the level of NO by 20%. This increased NO production was totally abolished by incubating the cells with R-954, a selective bradykinin B(1) antagonist. The release of NO from macrophages of STZ-treated mice incubated in the presence of LPS was more marked and reached approximately 220, 300 and 270% respectively from cells collected 8, 12 and 18 days after the STZ treatment. These significant increases were completely blocked by R-954 and were even below control values. Similarly the results showed that DBK stimulated by 50-75% the release of NO from macrophages of STZ-treated mice. The most marked stimulation was noted when the cells were collected 18 days after the treatment of the animals with STZ. Again in this set of experiments the B(1) antagonist completely blocked the release of NO which went even below control values. The results clearly suggest the upregulation of bradykinin B(1) receptors in mouse macrophages in the early phase of STZ-induced diabetes, an event that could even precede the onset of the diabetic hyperglycemia.
Assuntos
Diabetes Mellitus Experimental/imunologia , Diabetes Mellitus Tipo 1/imunologia , Ativação de Macrófagos/imunologia , Macrófagos Peritoneais/imunologia , Animais , Glicemia/efeitos dos fármacos , Bradicinina/química , Bradicinina/farmacologia , Células Cultivadas , Lipopolissacarídeos/farmacologia , Macrófagos Peritoneais/citologia , Macrófagos Peritoneais/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico/imunologia , Óxido Nítrico/metabolismo , Receptor B1 da Bradicinina/metabolismo , Estreptozocina/imunologia , Estreptozocina/farmacologiaRESUMO
The S(1)' and S(2)' subsite specificities of human tissue kallikrein 1 (KLK1) and human plasma kallikrein (HPK) were examined with the peptide series Abz-GFSPFRXSRIQ-EDDnp and Abz-GFSPFRSXRIQ-EDDnp [X=natural amino acids or S(PO(3)H(2))]. KLK1 efficiently hydrolyzed most of the peptides except those containing negatively charged amino acids at P(1)' and P(2)' positions. Abz-GFSPFRSSRIQ-EDDnp, as in human kininogen, is the best substrate for KLK1 and exclusively cleaved the R-S bond. All other peptides were cleaved also at the F-R bond. The synthetic human kininogen segment Abz-MISLMKRPPGFSPFRS(390)S(391)RI-NH(2) was hydrolyzed by KLK1 first at R-S and then at M-K bonds, releasing Lys-bradykinin. In the S(390) and S(391) phosphorylated analogs, this order of hydrolysis was inverted due to the higher resistance of the R-S bond. Abz-MISLMKRPPG-FSPFRSS(PO(3)H(2))(391)RI-NH(2) was hydrolyzed by KLK1 at M-K and mainly at the F-R bond, releasing des-(Arg(9))-Lys-Bk which is a B1 receptor agonist. HPK cleaved all the peptides at R and showed restricted specificity for S in the S(1)' subsite, with lower specificity for the S(2)' subsite. Abz-MISLMKRPPGFSPFRSSRI-NH(2) was efficiently hydrolyzed by HPK under bradykinin release, while the analogs containing S(PO(3)H(2)) were poorly hydrolyzed. In conclusion, S(1)' and S(2)' subsite specificities of KLK1 and HPK showed peculiarities that were observed with substrates containing the amino acid sequence of human kininogen.
Assuntos
Bradicinina/metabolismo , Cininogênios/metabolismo , Peptídeos/metabolismo , Calicreína Plasmática/metabolismo , Calicreínas Teciduais/metabolismo , Sequência de Aminoácidos , Bradicinina/química , Transferência Ressonante de Energia de Fluorescência , Humanos , Hidrólise , Cinética , Cininogênios/química , Cininas/metabolismo , Dados de Sequência Molecular , Peptídeos/química , Fosforilação , Proteínas Recombinantes/química , Especificidade por Substrato , ortoaminobenzoatos/químicaRESUMO
Prolyl oligopeptidase (POP, EC 3.4.21.26) is a member of a family of serine peptidases with post-proline cleaving activity towards peptides. It is located in the cytosol in active form but without hydrolytic activity on proteins or peptides higher than 30 amino acids. Its function is not well defined, but it is involved in central nervous system disorders. Here, we studied the substrate specificity of wild type POP (POPwt) and its C255T variant lacking the non-catalytic Cys(255). This residue is located in the seven-bladed beta-propeller domain that regulates the activity of POP. Fluorescence resonance energy transfer (FRET) peptides were used with sequences derived from bradykinin-containing region of human kininogen and flanked by Abz (ortho-aminobenzoic acid) and EDDnp [N-ethylenediamine-(2,4-dinitrophenyl)]. The peptide Abz-GFSPFRQ-EDDnp was taken as leader substrate for the synthesis of five series of peptides modified at the P(3), P(2), P'(1), P'(2) and P'(3) residues. The optimal amino acids in each position for POPwt resulted in the sequence RRPYIR that is very similar to the C-terminal sequence of neurotensin. The cyclic peptides c(G((n))FSPFR) (n=1-4) were hydrolyzed by POP; their cycloretro and cycloretro-inverso analogues were inhibitors in the micromolar range. The differences between POPwt and its C255T mutant in the hydrolysis of the series derived from Abz-GFSPFRQ-EDDnp were restricted to the non-prime site of the substrates. The kinetic data of hydrolysis and inhibition by the cyclic peptides are consistent with the structures of POP-substrate/inhibitor complexes and with the substrate specificity data obtained with linear FRET peptides. All together, these results give information about the POP-substrate/inhibitor interactions that further complete knowledge of this important oligopeptidase.
Assuntos
Bradicinina/química , Peptídeos/metabolismo , Serina Endopeptidases/metabolismo , Animais , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Cinética , Peptídeos/química , Peptídeos/farmacologia , Peptídeos Cíclicos/química , Peptídeos Cíclicos/metabolismo , Peptídeos Cíclicos/farmacologia , Prolil Oligopeptidases , Ligação Proteica , Proteínas Recombinantes/metabolismo , Serina Endopeptidases/genética , Especificidade por Substrato , SuínosRESUMO
Variation in the snake venom proteome is well documented and it is a ubiquitous phenomenon at all taxonomical levels. However, variation in the snake venom peptidome is so far not described. In this work we used mass spectrometry [liquid chromatography/mass spectrometry (LC/MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOFMS)] to explore sex-based differences among the venom peptides of eighteen sibling specimens of Bothrops jararaca of a single litter born and raised in the laboratory. MALDI-TOFMS analyses showed individual variability among the bradykinin-potentiating peptides (BPPs), and, interestingly, four new peptides were detected only in female venoms and identified by de novo sequencing as cleaved BPPs lacking the C-terminal Q-I-P-P sequence. Similar results were obtained with venom from wild-caught adult non-sibling specimens of B. jararaca and in this case we were able to identify the gender of the specimen by analyzing the MALDI-TOF profile of the peptide fraction and finding the cleaved peptides only in female venoms. Synthetic replicates of the cleaved BPPs were less potent than the full-length BPP-10c in potentiating the bradykinin hypotensive effect, suggesting that the C-terminus is critical for the interaction of the BPPs with their mammalian molecular targets. This work represents a comprehensive mass spectrometric analysis of the peptide fraction of B. jararaca venom and shows for the first time sex-based differences in the snake venom peptidome of sibling and non-sibling snakes and suggests that the BPPs may follow distinct processing pathways in female and male individuals.
Assuntos
Bothrops/metabolismo , Bradicinina/química , Cromatografia Líquida de Alta Pressão/métodos , Venenos de Crotalídeos/química , Mapeamento de Peptídeos/métodos , Peptídeos/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Animais , Feminino , Masculino , Sensibilidade e Especificidade , Análise de Sequência de Proteína/métodos , Fatores SexuaisRESUMO
Two bradykinin-related peptides (Protopolybiakinin-I and Protopolybiakinin-II) were isolated from the venom of the social wasp Protopolybia exigua by RP-HPLC, and sequenced by Edman degradation method. Peptide sequences of Protopolybiakinin-I and Protopolybiakinin-II were DKNKKPIRVGGRRPPGFTR-OH and DKNKKPIWMAGFPGFTPIR-OH, respectively. Synthetic peptides with identical sequences to the bradykinin-related peptides and their biological functions were characterized. Protopolybiakinin-I caused less potent constriction of the isolated rat ileum muscles than bradykinin (BK). In addition, it caused degranulation of mast cells which was seven times more potent than BK. This peptide causes algesic effects due to the direct activation of B(2)-receptors. Protopolybiakinin-II is not an agonist of rat ileum muscle and had no algesic effects. However, Protopolybiakinin-II was found to be 10 times more potent as a mast cell degranulator than BK. The amino acid sequence of Protopolybiakinin-I is the longest among the known wasp kinins.
Assuntos
Bradicinina/química , Bradicinina/genética , Peptídeos/química , Venenos de Vespas/química , Sequência de Aminoácidos , Animais , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Dados de Sequência Molecular , Nociceptores/efeitos dos fármacos , Peptídeos/síntese química , Peptídeos/genética , Ratos , Alinhamento de Sequência , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Venenos de Vespas/genética , VespasRESUMO
Bradykinin related peptides (BRPs) present in the water-soluble secretion and freshly dissected skin fragments of Phyllomedusa hypochondrialis were investigated by mass spectrometry techniques. Eighteen BRPs, along with their post-translational modifications, were characterized in the secretion by de novo MS/MS sequencing and direct MALDI imaging experiments of the frog skin. These molecules revealed strong sequence similarities to the main plasma kinin of some mammals and reptiles. Such a diversity of molecules, within the same peptide family, belonging to a single amphibian species may be related to functional specializations of these peptides and a variety of corresponding receptors that might be present in a number of different predators. Also, a novel analog, [Val]1,[Thr]6-bradykinyl-Gln,Ser had its biological activity positively detected in cell culture expressing the human bradykinin B2 receptor and in guinea pig ileum preparations.
Assuntos
Bradicinina/análogos & derivados , Bradicinina/química , Ranidae/metabolismo , Sequência de Aminoácidos , Animais , Células CHO , Cricetinae , Cricetulus , Feminino , Cobaias , Humanos , Hidroxiprolina/química , Espectrometria de Massas , Dados de Sequência Molecular , Músculo Liso/citologia , Músculo Liso/metabolismo , Ranidae/classificação , Receptor B2 da Bradicinina/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , TransfecçãoRESUMO
The defensive strategy of amphibians against predator attack relies heavily on the secretion of noxious/toxic chemical cocktails from specialized skin granular glands. Bioactive peptides constitute a major component of secretions in many species and the most complex are produced by neotropical leaf frogs of the sub-family Phyllomedusinae. We recently reported that these skin secretions contain elements of both the granular gland peptidome and transcriptome and that polyadenylated mRNAs constituting the latter are protected from degradation by interactions with endogenous amphipathic peptides. This thus permits parallel amino acid sequencing of peptides and nucleic acid sequencing of cloned precursor transcripts from single lyophilized samples of secretion. Here we report that the protection afforded is sufficiently robust to permit transcriptome studies by cloning of full-length polyadenylated peptide precursor encoding mRNAs from libraries constructed using ambient temperature air-dried skin from recently deceased specimens as source material. The technique was sufficiently sensitive to permit the identification of cDNAs encoding antimicrobial peptides constituted by six different isoforms of phylloseptin and two dermaseptins. Also, for the first time, establishment of the nucleic acid and amino acid sequence of the precursor encoding the phyllomedusine frog skin bradykinin-related peptide, phyllokinin, from cloned cDNA, was achieved. These data unequivocally demonstrate that the granular gland transcriptome persists in air-dried amphibian skin--a finding that may have fundamental implications in the study of archived materials but also in the wider field of molecular biology.
Assuntos
Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/genética , Anuros/genética , Pele/metabolismo , Sequência de Aminoácidos , Proteínas de Anfíbios/química , Proteínas de Anfíbios/genética , Proteínas de Anfíbios/metabolismo , Animais , Peptídeos Catiônicos Antimicrobianos/metabolismo , Anuros/classificação , Anuros/metabolismo , Sequência de Bases , Bradicinina/química , Bradicinina/genética , Bradicinina/metabolismo , Biblioteca Gênica , Cininas/química , Cininas/genética , Cininas/metabolismo , Dados de Sequência Molecular , Preservação Biológica , Proteoma/genética , Precursores de RNA/química , Precursores de RNA/metabolismo , RNA Mensageiro/metabolismo , Pele/química , América do Sul , Transcrição GênicaRESUMO
M 3 A oligopeptidases from Escherichia coli, with hydrolytic properties similar to Zn-dependent mammalian thimet oligopeptidase (EP 24.15) and neurolysin (EP 24.16), were studied aiming at identification of comparative enzyme and substrate specificity, hydrolytic products, and susceptibility to inhibitors. Fluorescent peptides, neurotensin (NT) and bradykinin (BK), were used as substrates for bacterial lysates. Bacterial enzymes were totally inhibited by o-phenanthrolin, JA-2 and partially by Pro-Ile, but not by leupeptin, PMSF, E-64, and Z-Pro-Prolinal, using internally quenched Abz-GFSPFRQ-EDDnp as substrate. The molecular mass of the bacterial oligopeptidase activity (77--78 kDa) was determined by gel filtration, and the effect of inhibitors, including captopril, suggested that it results from a combination of oligopeptidase A (OpdA) and peptidyl dipeptidase Dcp (77.1 and 77.5 kDa, respectively). Recombinant OpdA cloned from the same E. coli strain entirely reproduced the primary cleavage of fluorescent peptides, NT and BK, by the bacterial lysate. Genes encoding these M 3 A enzymes were those recognized in E. coli genome, bearing identity at the amino acid level (25--31%) with mammalian Zn-dependent oligopeptidases. We also describe a substrate, Abz-GFSPFRQ-EDDnp, that differentiates bacterial and mammalian oligopeptidases.
Assuntos
Bradicinina/química , Escherichia coli/enzimologia , Metaloendopeptidases/química , Neurotensina/química , Peptídeo Hidrolases/química , Sequência de Aminoácidos , Ativação Enzimática , Cinética , Dados de Sequência Molecular , Peso Molecular , Ligação Proteica , Homologia de Sequência de Aminoácidos , Especificidade por SubstratoRESUMO
We investigated the inhibition of trypsin, human tissue (hK1) and human plasma kallikrein (HuPK), papain, and cathepsin L, B, and X by synthetic cyclic, cycloretro-isomer, cycloretro-inverso, and linear peptides derived from the C-terminal sequence of bradykinin. c(FSPFRG) and Ac-FSPFRG-NH2 were taken as the references for cyclic and linear peptides, respectively. Longer and more flexible analogs of them with addition of 2, 3, or 4 Gly and cycloretro-isomer and cycloretro-inverso analogs of c(FSPFRG) and c(GGGFSPFRG) were obtained and assayed. The susceptibility to hydrolysis of the peptides to all proteases was also examined. The highest affinities were found for c(FSPFRG) with hK1, Ac-GGFSPFRG-NH2 with HuPK, and psi (NHCO) c(fspfrG) with cathepsin L. The Ki values for cathepsin B and X with cyclic peptides were lower than those of linear peptides. The serine proteases hydrolyzed all linear and cyclic peptides, except c(FSPFRG) and c(GFSPFRG). The cysteine proteases hydrolyzed only the linear peptides, which were poor substrates. Although the Ki values obtained in the current work were in the microM range, the cyclic and cycloretro-inverso peptides seem to be a promising approach to develop efficient and resistant to hydrolysis inhibitors for the kallikreins and lysosomal cysteine proteases.
Assuntos
Bradicinina/química , Inibidores de Cisteína Proteinase/química , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Inibidores de Serina Proteinase/química , Cisteína Endopeptidases/metabolismo , Inibidores de Cisteína Proteinase/síntese química , Inibidores de Cisteína Proteinase/farmacologia , Humanos , Estrutura Molecular , Oligopeptídeos/síntese química , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Serina Endopeptidases/metabolismo , Inibidores de Serina Proteinase/síntese química , Inibidores de Serina Proteinase/farmacologiaRESUMO
N-Terminally and internally labeled analogues of the hormones angiotensin (AII, DRVYIHPF) and bradykinin (BK, RPPGFSPFR) were synthesized containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC). TOAC replaced Asp1 (TOAC1-AII) and Val3 (TOAC3-AII) in AII and was inserted prior to Arg1 (TOAC0-BK) and replacing Pro3 (TOAC3-BK) in BK. The peptide conformational properties were examined as a function of trifluoroethanol (TFE) content and pH. Electron paramagnetic resonance spectra were sensitive to both variables and showed that internally labeled analogues yielded rotational correlation times (tauC) considerably larger than N-terminally labeled ones, evincing the greater freedom of motion of the N-terminus. In TFE, tauC increased due to viscosity effects. Calculation of tau(Cpeptide)/tau(CTOAC) ratios indicated that the peptides acquired more folded conformations. Circular dichroism spectra showed that, except for TOAC1-AII in TFE, the N-terminally labeled analogues displayed a conformational behavior similar to that of the parent peptides. In contrast, under all conditions, the TOAC3 derivatives acquired more restricted conformations. Fluorescence spectra of AII and its derivatives were especially sensitive to the ionization of Tyr4. Fluorescence quenching by the nitroxide moiety was much more pronounced for TOAC3-AII. The conformational behavior of the TOAC derivatives bears excellent correlation with their biological activity, since, while the N-terminally labeled peptides were partially active, their internally labeled counterparts were inactive [Nakaie, C. R., et al., Peptides 2002, 23, 65-70]. The data demonstrate that insertion of TOAC in the middle of the peptide chain induces conformational restrictions that lead to loss of backbone flexibility, not allowing the peptides to acquire their receptor-bound conformation.
Assuntos
Angiotensina II/química , Bradicinina/química , Óxidos N-Cíclicos/química , Marcadores de Spin , Angiotensina II/metabolismo , Angiotensina II/farmacologia , Animais , Bradicinina/metabolismo , Bradicinina/farmacologia , Dicroísmo Circular , Óxidos N-Cíclicos/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Concentração de Íons de Hidrogênio , Conformação Proteica , Espectrometria de Fluorescência , Relação Estrutura-AtividadeRESUMO
Angiotensin I-converting enzyme (ACE) is a dipeptidyl-carboxypeptidase expressed in endothelial, epithelial and neuroepithelial cells. It is composed of two domains, known as N- and C-domains, and it is primarily involved in blood pressure regulation. Although the physiological functions of ACE are not limited to its cardiovascular role, it has been an attractive target for drug design due to its critical role in cardiovascular and renal disease. We examined natural structures based on bradykinin-potentiating peptides (BPPs) extracted from Bothrops jararaca venom for ACE inhibition. Modeling, docking and molecular dynamics were used to study the conserved residues in the S2', S1' and S1 positions that allow enzyme-substrate/inhibitor contacts. These positions are conserved in other oligopeptidases, and they form tight and non-specific contacts with lisinopril, enalapril and BPP9a inhibitors. The only specific inhibitor for human somatic ACE (sACE) was BPP9a, which is instable in the N-sACE-BPP9a complex due to repulsive electrostatic interactions between Arg P4-Arg 412 residues. Specificity for the C-terminal domain in human sACE inhibition was confirmed by electrostatic interaction with the Asp 1008 residue. Peptide-like BPP structures, naturally developed by snakes across millions of years of evolution, appear to be good candidates for the development of domain-selective ACE inhibitors with high stability and improved pharmacological profiles.