ABORDAGEM METALOPROTEÔMICA DO MERCÚRIO EM LEITE MATERNO DE COMUNIDADES DA BACIA AMAZÔNICA - BRASIL

Abstract

Mercury is a potentially toxic element with a wide distribution on the Amazonian environment. This metal is dangerous and responsible for environmental contaminations and human intoxications as it is capable to biomagnifications and bioaccumulate throughout the food chains becoming the main way of exposing the riverine Amazonian communities to methylmercury to whom the main diet is fish. Therefore, studies related to mercury toxicity are of fundamental importance to health and life quality of the Amazonian communities. This study aimed to detect and evaluate possible proteic biomarkers of mercury toxicity in samples of human milk collected in riverine populations of Madeira and Negro rivers in the Brazilian Amazon. Initially total mercury was determined in the hair of breast feeding women to identify who were contaminated with mercury followed by the obtaining of the proteome of milk samples by two-dimensional electrophoresis (2D PAGE) after precipitation of proteins in half acetone. On the proteic spots obtained in the process of protein fractionation of milk samples, detection of mercury was carried out by atomic absorption spectrometry in graphite furnace(GFAAS), where the results showed that mercury was bonded in proteins of molecular weight around 14-26 kDa. The concentration determination of total mercury by GFAAS was also carried out with milk in natura, lyophilized milk and the proteic pellets aiming a mass balance of mercury related to the concentration of this element on milk and pellets. The measurements of mass balance permitted to observe that, in relation to the milk samples from Madeira River, about 85 to 95%of the mercury present in the lyophilized milk is on the proteic fraction. In relation to the breastfeeding women of the Negro River, about 50% of the total mercury is bound in the proteic fraction and the difference of 51% might be bound to the lipidic fraction. However, more studies in this line of research need to be pursued to achieve more robust conclusions.