Interações de peptídeos de cadeias curtas e bicamadas lipídicas: estudo biofísico e reflexos sobre a atividade biológica
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Data
2018-11-26
Autores
Martins, Danúbia Batista
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O uso de peptídeos bioativos em antibioticoterapia tem dentre suas vantagens principais a reduzida possibilidade de desenvolvimento de resistência, uma vez que o alvo são os fosfolipídios constituintes da membrana celular. Muitos desses peptídeos são de cadeia curta, com amplo espectro de atividade contra bactérias e contra fungos, e com baixa citotoxicidade. Mecanismos de seletividade na ação de peptídeos bioativos vêm sendo investigados como forma de dirigir modificações estruturais que aperfeiçoem suas ações terapêuticas, minimizando efeitos tóxicos ou indesejáveis. Por serem predominantemente catiônicos, apresentam interação preferencial com bicamadas lipídicas aniônicas. Os peptídeos estudados neste trabalho são a Jelleine-I e dois análogos (JIF2W e JIF2WR) sintetizados com algumas modificações de resíduos na sequência primária, e a Protonectin isolada e em mistura com Protonectin (1-6). Estudos preliminares por dinâmica molecular sugeriram a formação de agregados na Jelleine-I em meio aquoso e em ambientes que modelam as características físico-químicas de membranas celulares, como as micelas do surfactante dodecil sulfato de sódio (SDS). Informações semelhantes foram também obtidas por meios computacionais para a Protonectin. Entretanto, este peptídeo quando em mistura com Protonectin (1-6), apresenta menor tendência à agregação em meio aquoso e em SDS. Outros estudos mostraram ainda que esta mistura apresenta atividades biológicas aumentadas. Neste trabalho realizou-se uma análise biofísica desses peptídeos em relação à formação de agregados, eficiência e seletividade, avaliados na presença de ambientes de caráter zwitteriônico e aniônicos, utilizando medidas de espectroscopia de FTIR, dicroísmo circular (CD) e fluorescência além de Potencial Zeta e determinação de atividades biológicas. Mudanças estruturais em diferentes ambientes foram verificadas tanto para a família das Jelleinas como para as Protonectinas na interação com bicamadas lipídicas, assim como também variações na formação da agregação. Nestas interações os peptídeos mostraram-se seletivos e com maior afinidade por bicamadas lipídicas de caráter aniônico. Biologicamente, ambas as famílias apresentaram baixa atividade hemolítica, sendo a Jelleíne-I e o análogo JIF2WR ativos principalmente contra bactérias Gram-positivas, enquanto a Protonectin mostrando-se mais ativa contra células tumorais, com uma tendência de melhor eficiência na combinação terapêutica em mistura com a Protonectin (1-6) na proporção 1:1.
The use of bioactive peptides in antibiotic therapy has among its main advantages the reduced possibility of resistance development, since the target are the phospholipids constituting the cell membrane. Many of these peptides are short chain, with broad spectrum of activity against bacteria and against fungi, and with low cytotoxicity. Mechanisms of selectivity in the action of bioactive peptides have been investigated as a way of directing structural modifications that improve their therapeutic actions, minimizing toxic or undesirable effects. Because they are predominantly cationic, they present preferential interaction with anionic lipid bilayers. The peptides studied in this work are Jelleine-I and two analogues (JIF2W and JIF2WR) synthesized with some modifications of residues in the primary sequence, and Protonectin isolated and in admixture with Protonectin (1-6). Preliminary molecular dynamics studies have suggested the formation of aggregates in Jelleine-I in aqueous media and in environments that model the physico-chemical characteristics of cell membranes, such as sodium dodecyl sulfate (SDS) surfactant micelles. Similar information was also obtained by computational means for Protonectin. However, this peptide when mixed with Protonectin (1-6), presents a lower tendency to aggregation in aqueous medium and in SDS. Other studies have also shown that this mixture has increased biological activities. In this work a biophysical analysis of these peptides was performed in relation to the formation of aggregates, efficiency and selectivity, evaluated in the presence of zwitterionic and anionic environments, using measurements of FTIR spectroscopy, circular dichroism (CD) and fluorescence in addition to Zeta Potential and determination of biological activities. Structural changes in different environments were verified for both the Jelleinas family and Protonectins in the interaction with lipid bilayers, as well as variations in aggregation formation. In these interactions the peptides were selective and with greater affinity for lipid bilayers of an anionic character. Biologically, both families had low hemolytic activity, with Jelleine-I and JIF2WR analogue being active mainly against Gram-positive bacteria, whereas Protonectin was more active against tumor cells, with a trend of better efficiency in the combination therapy with Protonectin (1-6) in the ratio 1: 1.
The use of bioactive peptides in antibiotic therapy has among its main advantages the reduced possibility of resistance development, since the target are the phospholipids constituting the cell membrane. Many of these peptides are short chain, with broad spectrum of activity against bacteria and against fungi, and with low cytotoxicity. Mechanisms of selectivity in the action of bioactive peptides have been investigated as a way of directing structural modifications that improve their therapeutic actions, minimizing toxic or undesirable effects. Because they are predominantly cationic, they present preferential interaction with anionic lipid bilayers. The peptides studied in this work are Jelleine-I and two analogues (JIF2W and JIF2WR) synthesized with some modifications of residues in the primary sequence, and Protonectin isolated and in admixture with Protonectin (1-6). Preliminary molecular dynamics studies have suggested the formation of aggregates in Jelleine-I in aqueous media and in environments that model the physico-chemical characteristics of cell membranes, such as sodium dodecyl sulfate (SDS) surfactant micelles. Similar information was also obtained by computational means for Protonectin. However, this peptide when mixed with Protonectin (1-6), presents a lower tendency to aggregation in aqueous medium and in SDS. Other studies have also shown that this mixture has increased biological activities. In this work a biophysical analysis of these peptides was performed in relation to the formation of aggregates, efficiency and selectivity, evaluated in the presence of zwitterionic and anionic environments, using measurements of FTIR spectroscopy, circular dichroism (CD) and fluorescence in addition to Zeta Potential and determination of biological activities. Structural changes in different environments were verified for both the Jelleinas family and Protonectins in the interaction with lipid bilayers, as well as variations in aggregation formation. In these interactions the peptides were selective and with greater affinity for lipid bilayers of an anionic character. Biologically, both families had low hemolytic activity, with Jelleine-I and JIF2WR analogue being active mainly against Gram-positive bacteria, whereas Protonectin was more active against tumor cells, with a trend of better efficiency in the combination therapy with Protonectin (1-6) in the ratio 1: 1.
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Palavras-chave
Jelleine-I, Protonectin, Agregação, Peptídeos antimicrobianos, Peptídeos anticâncer, Interações Peptídeos-Bicamadas Lipídicas, Modelos de Membrana, Técnicas Espectroscópicas, Aggregation, Antimicrobial peptides, Peptide-Lipid bilayer interactions, Membrane Models, Spectroscopic Techniques