Modulation of the pharmacological activities of secretory phospholipase A2 from Crotalus durissus cascavella induced by naringin.

In this work we have characterized the action of the naringin, a flavonoid found in grapefruit and known for its various pharmacological effects, which include antioxidant blood lipid lowering and anticancer activity, on the structure and biochemical activities of a secretory phospholipase A (sPLA2) from Crotalus durissus cascavella, an important protein involved in the releasinge of arachidonic acid in phospholipid membranes. sPLA2 was incubated with naringin (mol:mol) at 37 °C and a discrete reduction in the UV scanning signal and a modification of the circular dichroism spectra were observed after treatment with naringin, suggesting modifications of the secondary structure of the protein. This flavonoid was able to decrease enzymatic activity and some pharmacological effects, such as myonecrosis, platelet aggregation, and neurotoxic activity caused by sPLA2, however, the inflammatory effect was not affected by naringin. In addition, small angle X-ray scattering (SAXS) data were collected for sPLA2 and naringin-treated sPLA2 to evaluate possible modifications of the protein structure. These structural investigations have shown that sPLA2 is an elongated dimer in solution and after treatment with naringin a conformational change in the dimeric configuration was observed. Our results suggest that structural modification may be correlated with the loss of enzymatic activity and alterations in pharmacological properties.

Analysis of Molecular Changes Induced By Mineral Trioxide Aggregate On sPLA2.

The aim of this study was to analyze the effects of MTA on the structure and enzymatic activity of sPLA2 in order to provide subsidies for improvement in the formulation of the product. MTA powder was incubated for 60 min in the presence of sPLA2 and was analyzed by chromatography, electrospray mass (ESI-MS) and small-angle X-ray scattering (SAXS). It was find that the elution profile, retention time, and fragmentation of sPLA2 were altered after treatment with MTA. Calcium was the MTA component that most amplified the inflammatory signal. Significant interactions were found between MTA and sPLA2, which could aid in our understanding of the mechanisms of action of MTA during the inflammatory process and it may facilitate the structural modification of MTA, thereby improving its biological safety and consequently the rate of the treatment success.

Purification and preliminary crystallographic analysis of a new Lys49-PLA2 from B. Jararacussu.

BjVIII is a new myotoxic Lys49-PLA2 isolated from Bothrops jararacussu venom that exhibits atypical effects on human platelet aggregation. To better understand the mode of action of BjVIII, crystallographic studies were initiated. Two crystal forms were obtained, both containing two molecules in the asymmetric unit (ASU). Synchrotron radiation diffraction data were collected to 2.0 A resolution and 1.9 A resolution for crystals belonging to the space group P2(1)2(1)2(1) (a = 48.4 A, b = 65.3 A, c = 84.3 A) and space group P3(1)21 (a = b = 55.7 A, c = 127.9 A), respectively. Refinement is currently in progress and the refined structures are expected to shed light on the unusual platelet aggregation activity observed for BjVIII.

Fluorescent tetraruthenated porphyrins embedded in monolithic SiO2 gels by the sol-gel process.

In this work silica gels have been prepared by a sol-gel method using tetraethylorthosilicate as gel precursor. The tetraruthenated porphyrins H2(3-TRPyP), Co(3-TRPyP), and H2(4-TRPyP) were incorporated into the systems during gel formation without problems commonly found in the process, such as aggregation. Spectroscopic studies of the resulting silica gels revealed the presence of absorption bands in the range 200-400 nm associated with the transitions of the groups ruthenium-bipyridine, along with the Soret band at the same wavelengths observed in solution. The porphyrins were found to preserve fluorescence emission properties in the range 650-700 nm even after the aging period. Study of the thermal behavior and decomposition kinetics evidenced that the porphyrin H2(4-TRPyP) is the least stable of the group and that all compounds decompose according to first-order kinetics.

Analysis of molecular changes induced by mineral trioxide aggregate on spla2

Abstract The aim of this study was to analyze the effects of MTA on the structure and enzymatic activity of sPLA2 in order to provide subsidies for improvement in the formulation of the product. MTA powder was incubated for 60 min in the presence of sPLA2 and was analyzed by chromatography, electrospray mass (ESI-MS) and small-angle X-ray scattering (SAXS). It was find that the elution profile, retention time, and fragmentation of sPLA2 were altered after treatment with MTA. Calcium was the MTA component that most amplified the inflammatory signal. Significant interactions were found between MTA and sPLA2, which could aid in our understanding of the mechanisms of action of MTA during the inflammatory process and it may facilitate the structural modification of MTA, thereby improving its biological safety and consequently the rate of the treatment success.

Resumo O objetivo deste estudo foi analisar os efeitos do MTA na estrutura e atividade enzimática da sPLA2 a fim de fornecer subsídios para melhoria na formulação do produto. O MTA em pó foi incubado por 60 min na presença de sPLA2 e analisado por cromatografia, espectroscopia de massa por eletropulverização (ESI-MS) e espalhamento de raios-X de baixo ângulo (SAXS). Encontrou-se que o perfil de eluição, o tempo de retenção e a fragmentação da sPLA2 foram alterados após o tratamento com MTA. O cálcio foi o componente do MTA que mais ampliou o sinal inflamatório. Encontraram-se interações significativas entre o MTA e o sPLA2, o que poderia auxiliar na compreensão dos mecanismos de ação do MTA durante o processo inflamatório e facilitar a modificação estrutural do MTA, melhorando sua segurança biológica e consequentemente a taxa de sucesso do tratamento.

A catalytically inactive Lys49 PLA2 isoform from Bothrops jararacussu venom that stimulates insulin secretion in pancreatic beta cells.

A new secretory phospholipase A2 (sPLA2) isoform from Bothrops jararacussu venom (BjVIII) has been characterized by causing platelet aggregation, an absent activity in BthTx-I, Prtx-I and PrTx-II sPLA2s. According to our results, BjVIII also enhances insulin release by the pancreatic beta cells. The complete amino acid sequence of the new isoform was determined by Edman degradation and de novo peptide sequencing. These analyses showed a G35K amino acid modification for BjVIII in comparison with BthTx-I, PrTx-I and Prtx-II, a structural difference that has been related to the conflicting biological activities among BjVIII and other Lys49 sPLA2s. The whole set of evidences collected in this work indicates that, besides the C-terminal region and B-wing of PLA2, the calcium binding loop in BjVIII should be considered as an important region, involved in the pharmacological effects of Lys49-sPLA2 isoforms from the Bothrops genus.