Avaliação do desenvolvimento de girassol por meio de analise de proteinas e metaloproteinas / Evaluation of sunflower development based on protein metalloprotein analysis

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This work describes an evaluation of sunflower (Helianthus annuus L.) growth when it is submitted to seven treatments, and their interrelation with proteins and metalloproteins analyses. Metal ion solutions (Cd, Cu, Pb and Zn) were added to the substrate in four treatments. In another two, used as controls, the plants were irrigated only with deionized water. Finally, in the seventh treatment, a solution called "mixed ions solution", simultaneously containing the four metal ions was used. The sunflower height, biomass production and nutrient distribution and translocation were evaluated. Sunflower plants contaminated with mixed solution are more affected in terms of physiological parameters. The influence of metal species on the protein composition was also investigated. For that, the extraction of sunflower proteins present in leaves, stem and root tissue was carried out. The total protein content in all extracts was determined according to the Bradford method. The leaves proteins were separated using SDS-PAGE electrophoresis. Leaves from plants irrigated with zinc were more affected in terms of protein expression. In such case, there was a significant decrease of protein amounts and the suppression of some of them. This is explained by the excessive generation of reactive oxygen species that induced an oxidative stress, which was confirmed by the enzymatic activity analyses of catalase, superoxide dismutase and glutathione reductase. In order to obtain more details about the changes in protein composition, leaf proteins were also separated using two-dimensional electrophoresis. In this analysis it was possible to detect about 260 protein spots and confirm that the proteins of plants contaminated with zinc were more affected. In another part of this work, the identification of the metal ions bound to the proteins was carried out. For that, 43 protein bands obtained from SDS-PAGE separation were mapped using synchrotron radiation X-ray fluorescence analysis. The fluorescence intensities of 11 chemical species were evaluated by the Kohonen Neural Network. This chemometric tool selected six samples in which the quantitative analysis of metal ions are made. For that, the bands were decomposed by two different systems (microwave-assisted sample combustion and focused microwave oven). In these samples, the correlation between the formation and/or preservation of metalloproteins and the substrate were investigated. The proteins proceeding from sunflowers plants without contamination showed high metal ions levels so that it is possible to conclude that important metalloproteins and enzymes participate in metabolic processes to avoid the adverse effects provoked by metal ion excess, particularly when zinc is considered.

ASSUNTO(S)

girassol protein proteina contamination metalloprotein metaloproteinas contaminação sunflower

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