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Publication
Interacção de complexos de vanádio-citrato com a bomba de cálcio de retículo sarcoplasmático
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Advisor(s)
Abstract(s)
A bomba de cálcio de retículo sarcoplasmático (RS) foi caractenzada e
comparada em dois modelos animais (coelho e dourada). Demonstrou-se que as
preparações de Ca2+-ATPase exibem uma disparidade na constituição proteica, assim
como, na quantidade relativa de cada proteína. Esta diferença também foi observada nas
actividades hidrolítica e de acumulação de Ca f.
Através de uma combinação de estudos cinéticos e espectroscópicos, avahou-se
a interacção de soluções de vanadato (contendo várias espécies oligoméricas), de zinco,
assim como, de complexos de vanádio-citrato e citrato com a Ca ' -ATPase de RS de
coelho. Relativamente aos efeitos promovidos pelas soluções de vanadato e zinco,
verificou-se que a espécie decamérica é o inibidor mais potente da actividade ATPásica.
O zinco, contrariamente ao vanadato, induz um decréscimo da eficiência da bomba.
Adicionalmente, observou-se que estes iões metálicos não exibem um efeito inibitório
sinergético na Ca2+-ATPase. As soluções de complexos vanadato-citrato 2 mM
induziram uma inibição da acumulação de Ca2 igual ou superior relativamente às
espécies oligoméricas de vanadato que as constituem. Através V-RMN foi possível
confirmar a interacção destes complexos com a proteína, atribuindo-se os efeitos
inibitórios observados aos complexos em si ou a uma acção combinada com as espécies
de vanadato.
Por fim, avaliou-se a acumulação de vanádio em músculo esquelético de
dourada, após contaminação com duas soluções de vanadato 5 mM ( metavanadato^ e
"decavanadato") durante um período de exposição de 1, 6 e 12 horas. Ambas soluções
de vanadato induzem um aumento na quantidade do metal nos indivíduos
contaminado
The sarcoplasmic reticulum (SR) calcium pump was characterized and compared in two animal models (rabbit and gilthead seabream). It was demonstrated that Ca2+-ATPase preparations exhibit differences in the protein constitution, as well as, in the relative amount of each protein. This difference was also observed in the hidrolytical activity and Ca2f accumulation. ^ Through a combination of kinetic and spectroscopic studies, the interaction of vanadate solutions (containing several oligomeric species) vanadium-citrate complexes, citrate and zinc was evaluated with the rabbit SR Ca -ATPase. Relatively to the promoted effects by vanadate solutions and zinc, it was verified that decameric species is the strongest inhibitor of the ATPasic activity. Zinc, on the contrary to vanadate, induces a decrease in the efficiency ofthe pump. Additionally it was observed that these metal ions do not exhibit a synergistic inhibitory effect in the SR Ca f-ATPase. The 2 mM solutions of vanadate-citrate complexes induced a similar or stronger inhibition of the Ca2" accumulation, relatively to the oligomeric vanadate species that constitute them. Through 51V-NMR, it was possible to confirm the interaction of these complexes with the protein, attributing the observed inhibitory effects to the complexes or to a combined action with vanadate species. At last, the accumulation of vanadium in the muscle of gilthead seabream after contamination with two 5 mM vanadate solutions ("metavanadate and decavanadate ) during an exposure period of 1, 6 and 12 hours was evaluated. Both vanadate solutions induce an increase in the metal quantity in the contaminated individuais.
The sarcoplasmic reticulum (SR) calcium pump was characterized and compared in two animal models (rabbit and gilthead seabream). It was demonstrated that Ca2+-ATPase preparations exhibit differences in the protein constitution, as well as, in the relative amount of each protein. This difference was also observed in the hidrolytical activity and Ca2f accumulation. ^ Through a combination of kinetic and spectroscopic studies, the interaction of vanadate solutions (containing several oligomeric species) vanadium-citrate complexes, citrate and zinc was evaluated with the rabbit SR Ca -ATPase. Relatively to the promoted effects by vanadate solutions and zinc, it was verified that decameric species is the strongest inhibitor of the ATPasic activity. Zinc, on the contrary to vanadate, induces a decrease in the efficiency ofthe pump. Additionally it was observed that these metal ions do not exhibit a synergistic inhibitory effect in the SR Ca f-ATPase. The 2 mM solutions of vanadate-citrate complexes induced a similar or stronger inhibition of the Ca2" accumulation, relatively to the oligomeric vanadate species that constitute them. Through 51V-NMR, it was possible to confirm the interaction of these complexes with the protein, attributing the observed inhibitory effects to the complexes or to a combined action with vanadate species. At last, the accumulation of vanadium in the muscle of gilthead seabream after contamination with two 5 mM vanadate solutions ("metavanadate and decavanadate ) during an exposure period of 1, 6 and 12 hours was evaluated. Both vanadate solutions induce an increase in the metal quantity in the contaminated individuais.
Description
Dissertação de mest. em Biotecnologia, Departamento de Química e Bioquímica da Faculdade de Ciêicias e Tecnologia, Univ. do Algarve, 2004
Keywords
Ca2'-ATPase Retículo sarcoplasmático Músculo esquelético Vanádio Zinco Complexos vanádio-citrato