RESUMO
CIDEM-501 is a hybrid antimicrobial peptide rationally designed based on the structure of panusin and panulirin template peptides. The new peptide exhibits significant antibacterial activity against multidrug-resistant pathogens (MIC = 2-4 µM) while conserving no toxicity in human cell lines. We conducted molecular dynamics (MD) simulations using the CHARMM-36 force field to explore the CIDEM-501 adsorption mechanism with different membrane compositions. Several parameters that characterize these interactions were analyzed to elucidate individual residues' structural and thermodynamic contributions. The membrane models were constructed using CHARMM-GUI, mimicking the bacterial and eukaryotic phospholipid compositions. Molecular dynamics simulations were conducted over 500 ns, showing rapid and highly stable peptide adsorption to bacterial lipids components rather than the zwitterionic eucaryotic model membrane. A predominant peptide orientation was observed in all models dominated by an electric dipole. The peptide remained parallel to the membrane surface with the center loop oriented to the lipids. Our findings shed light on the antibacterial activity of CIDEM-501 on bacterial membranes and yield insights valuable for designing potent antimicrobial peptides targeting multi- and extreme drug-resistant bacteria.
RESUMO
As other spiny lobsters, Panulirus argus is supposed to use preferentially proteins and lipids in energy metabolism, while carbohydrates are well digested but poorly utilized. The aim of this study was to evaluate the effect of dietary carbohydrate level on digestion and metabolism in the spiny lobster P. argus. We used complementary methodologies such as post-feeding flux of nutrients and metabolites, as well as measurements of α-amylase expression and activity in the digestive tract. Lobsters readily digested and absorbed carbohydrates with a time-course that is dependent on their content in diet. Lobster showed higher levels of free glucose and stored glycogen in different tissues as the inclusion of wheat flour increased. Modifications in intermediary metabolism revealed a decrease in amino acids catabolism coupled with a higher use of free glucose as carbohydrates rise up to 20%. However, this effect seems to be limited by the metabolic capacity of lobsters to use more than 20% of carbohydrates in diets. Lobsters were not able to tightly regulate α-amylase expression according to dietary carbohydrate level but exhibited a marked difference in secretion of this enzyme into the gut. Results are discussed to highlight the limitations to increasing carbohydrate utilization by lobsters. Further growout trials are needed to link the presented metabolic profiles with phenotypic outcomes.
RESUMO
Alpha-amylases are ubiquitously distributed throughout microbials, plants and animals. It is widely accepted that omnivorous crustaceans have higher α-amylase activity and number of isoforms than carnivorous, but contradictory results have been obtained in some species, and carnivorous crustaceans have been less studied. In addition, the physiological meaning of α-amylase polymorphism in crustaceans is not well understood. In this work we studied α-amylase in a carnivorous lobster at the gene, transcript, and protein levels. It was showed that α-amylase isoenzyme composition (i.e., phenotype) in lobster determines carbohydrate digestion efficiency. Most frequent α-amylase phenotype has the lowest digestion efficiency, suggesting this is a favoured trait. We revealed that gene and intron loss have occurred in lobster α-amylase, thus lobsters express a single 1830 bp cDNA encoding a highly conserved protein with 513 amino acids. This protein gives rise to two isoenzymes in some individuals by glycosylation but not by limited proteolysis. Only the glycosylated isoenzyme could be purified by chromatography, with biochemical features similar to other animal amylases. High carbohydrate content in diet down-regulates α-amylase gene expression in lobster. However, high α-amylase activity occurs in lobster gastric juice irrespective of diet and was proposed to function as an early sensor of the carbohydrate content of diet to regulate further gene expression. We concluded that gene/isoenzyme simplicity, post-translational modifications and low Km, coupled with a tight regulation of gene expression, have arose during evolution of α-amylase in the carnivorous lobster to control excessive carbohydrate digestion in the presence of an active α-amylase.
Assuntos
Proteínas de Artrópodes , Carnivoridade/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Palinuridae , alfa-Amilases , Animais , Proteínas de Artrópodes/biossíntese , Proteínas de Artrópodes/genética , DNA Complementar/genética , DNA Complementar/metabolismo , Glicosilação , Isoenzimas/biossíntese , Isoenzimas/genética , Palinuridae/genética , Palinuridae/metabolismo , Proteólise , alfa-Amilases/biossíntese , alfa-Amilases/genéticaRESUMO
In the present study, we aimed to determine the influence of ß-(1,3)-d-glucans on the LPS-induced pro-inflammatory cytokine response in the Monocyte Activation Test (MAT) for pyrogens, and on the LPS-induced febrile response in the Rabbit Pyrogen Test (RPT), thus evaluating the resulting effect in the outcome of each test. It was found that ß-(1,3)-d-glucans elicited the production of pro-inflammatory cytokines IL-1ß, IL-6 and TNF-α, also known as endogenous pyrogens, but not enough to classify them as pyrogenic according to MAT. The same ß-(1,3)-d-glucans samples were non-pyrogenic by RPT. However, ß-(1,3)-d-glucans significantly enhanced the LPS-induced pro-inflammatory cytokines response in MAT, insomuch that samples containing non-pyrogenic concentrations of LPS become pyrogenic. On the other hand, ß-(1,3)-d-glucans had no effect on sub-pyrogenic LPS doses in the RPT, but surprisingly, inhibited the LPS-induced febrile response of pyrogenic LPS concentrations. Thus, while ß-(1,3)-d-glucans could mask the LPS pyrogenic activity in the RPT, they exerted an overstimulation of pro-inflammatory cytokines in the MAT. Hence, MAT provides higher safety since it evidences an unwanted biological response, which is not completely controlled and is overlooked by the RPT.
Assuntos
Febre/induzido quimicamente , Lipopolissacarídeos/farmacologia , Monócitos/efeitos dos fármacos , Pirogênios/farmacologia , beta-Glucanas/farmacologia , Animais , Febre/imunologia , Humanos , Interleucina-1beta/imunologia , Interleucina-6/imunologia , Masculino , Monócitos/imunologia , Proteoglicanas , Coelhos , Fator de Necrose Tumoral alfa/imunologiaRESUMO
The melanization reaction promoted by the prophenoloxidase-activating system is an essential defense response in invertebrates subjected to regulatory mechanisms that are still not fully understood. We report here the finding and characterization of a novel trypsin inhibitor, named panulirin, isolated from the hemocytes of the spiny lobster Panulirus argus with regulatory functions on the melanization cascade. Panulirin is a cationic peptide (pI 9.5) composed of 48 amino acid residues (5.3 kDa), with six cysteine residues forming disulfide bridges. Its primary sequence was determined by combining Edman degradation/N-terminal sequencing and electrospray ionization-MS/MS spectrometry. The low amino acid sequence similarity with known proteins indicates that it represents a new family of peptidase inhibitors. Panulirin is a competitive and reversible tight-binding inhibitor of trypsin (Ki = 8.6 nm) with a notable specificity because it does not inhibit serine peptidases such as subtilisin, elastase, chymotrypsin, thrombin, and plasmin. The removal of panulirin from the lobster hemocyte lysate leads to an increase in phenoloxidase response to LPS. Likewise, the addition of increasing concentrations of panulirin to a lobster hemocyte lysate, previously depleted of trypsin-inhibitory activity, decreased the phenoloxidase response to LPS in a concentration-dependent fashion. These results indicate that panulirin is implicated in the regulation of the melanization cascade in P. argus by inhibiting peptidase(s) in the pathway toward the activation of the prophenoloxidase enzyme.
Assuntos
Proteínas de Artrópodes/metabolismo , Catecol Oxidase/metabolismo , Precursores Enzimáticos/metabolismo , Palinuridae/metabolismo , Inibidores da Tripsina/metabolismo , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/química , Proteínas de Artrópodes/genética , Catecol Oxidase/química , Catecol Oxidase/genética , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Precursores Enzimáticos/química , Precursores Enzimáticos/genética , Hemócitos/química , Hemócitos/citologia , Hemócitos/metabolismo , Lipopolissacarídeos/farmacologia , Dados de Sequência Molecular , Palinuridae/química , Palinuridae/genética , Tripsina/química , Inibidores da Tripsina/química , Inibidores da Tripsina/genéticaRESUMO
La administración intranasal de eritropoyetina humana recombinante con bajo contenido de ácido siálico (rHu-EPOb) puede ser empleada como un agente neuroprotector eficaz en el tratamiento de la isquemia cerebral. En el presente trabajo fueron administradas 10 µg de rHu-EPOb 3 veces al día durante 2 días, comenzando inmediatamente antes de la inducción de la isquemia focal transitoria en ratas. Los resultados demostraron que la administración nasal de rHu-EPOb mejoró significativamente el comportamiento neurológico en animales sometidos a isquemia focal transitoria y disminuyó el área de infarto en las diferentes zonas cerebrales estudiadas. La evaluación histopatológica de la zona del hipocampo de los animales sometidos al daño neuronal, evidenció ligeras alteraciones caracterizadas por la presencia de neuronas picnóticas. Los resultados mostraron el efecto neuroprotector de la administración intranasal de una formulación a partir de rHu-EPOb en ratas sometidas a isquemia focal transitoria y confirman la necesidad de realizar estudios clínicos para evaluar el posible efecto anti-isquémico de esta formulación.
Intranasal administration of recombinant human erythropoietin (rHu-EPOb) may be used lake an effective neuroprotective agent in treatment of cerebral ischemia. In present paper 10 µg of rHu-EPOb three times/day during 2 days were administered, starting immediately before induction of a transitory focal ischemia in rats. Results showed that nasal administration of rHu-EPOb improved significantly the neurologic behavior in animals underwent to transitory focal ischemia, and decreased infarction area in the different cerebral zones studied. Histopathological assessment of hippocampus zone of animal underwent to neuronal damage, showed slight alterations characterized by presence of pycnotic neurons. Results showed the neuroprotective effect of intranasal administration of a formula from rHu-EPOb in rats underwent to transitory focal ischemia, and confirm the need of clinical studies to assess the possible anti-ischemic effect of this formula.
Assuntos
Ratos , Eritropoetina , Isquemia Encefálica/tratamento farmacológicoRESUMO
Hemocyanin and phenoloxidase belong to the type-3 copper protein family, sharing a similar active center whereas performing different roles. In this study, we demonstrated that purified hemocyanin (450 kDa) from the spiny lobster Panulirus argus shows phenoloxidase activity in vitro after treatment with trypsin, chymotrypsin and SDS (0.1% optimal concentration), but it is not activated by sodium perchlorate or isopropanol. The optimal pHs of the SDS-activated hemocyanin were 5.5 and 7.0. Hemocyanin from spiny lobster behaves as a catecholoxidase. Kinetic characterization using dopamine, L-DOPA and catechol shows that dopamine is the most specific substrate. Catechol and dopamine produced substrate inhibition above 16 and 2 mM respectively. Mechanism-based inhibition was also evidenced for the three substrates, being less significant for L-DOPA. SDS-activated phenoloxidase activity is produced by the hexameric hemocyanin. Zymographic analysis demonstrated that incubation of native hemocyanin with trypsin and chymotrypsin, produced bands of 170 and 190 kDa respectively, with intense phenoloxidase activity. Three polypeptide chains of 77, 80 and 89 kDa of hemocyanin monomers were identified by SDS-PAGE. Monomers did not show phenoloxidase activity induced by SDS or partial proteolysis.
Assuntos
Hemocianinas/metabolismo , Monofenol Mono-Oxigenase/metabolismo , Palinuridae/enzimologia , 2-Propanol/farmacologia , Animais , Catecol Oxidase/química , Catecol Oxidase/metabolismo , Catecóis/metabolismo , Quimotripsina/metabolismo , Dopamina/metabolismo , Eletroforese em Gel de Poliacrilamida , Ativação Enzimática , Hemocianinas/química , Hemocianinas/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Levodopa/metabolismo , Peso Molecular , Monofenol Mono-Oxigenase/química , Palinuridae/química , Percloratos/farmacologia , Compostos de Sódio/farmacologia , Dodecilsulfato de Sódio/química , Especificidade por Substrato , Tripsina/metabolismoRESUMO
Para el cumplimiento de las buenas prácticas de laboratorio y de fabricación de parenterales, una de las exigencias es la validación de los ciclos de despirogenización que se emplean. En el presente trabajo se describe la validación de un ciclo de despirogenización por calor seco en un horno de convección. En la primera etapa se estudiaron características físicas del equipo como el tiempo requerido para alcanzar la temperatura establecida, su distribución, estabilidad, y la influencia de la carga en el patrón de calentamiento. Considerando los resultados de esta fase se estableció un proceso total de 7 h a 180 ºC. La segunda etapa consistió en la determinación del grado de despirogenización retando el proceso con bioindicadores de endotoxinas. La concentración de endotoxinas en los bioindicadores control y sometidos al proceso de despirogenización se cuantificó con el empleo del ensayo del lisado de amebocitos de limulus método de gelificación. La diferencia entre el contenido de endotoxinas en el control y los tratamientos fue de 2 400 U de endotoxinas, por lo que el proceso rindió una reducción logarítmica mínima de 4,6 log, la cual es mayor que el límite de 3 log establecido por la Farmacopea de los Estados Unidos