http://hdl.handle.net/11422/23 Wed, 08 Apr 2026 22:49:11 GMT 2026-04-08T22:49:11Z http://hdl.handle.net/11422/28450 Title: Modificações estruturais da Ca²⁺ATPase de eritrócito em diferentes estados formacionais estudadas por espectroscopia de fluorescência Author(s)/Inventor(s): Sampaio, Tatiana Lobo Coelho de Advisor: Vieyra, Adalberto Ramon Abstract: The structure of the plasma membrane erythrocyte Ca²-ATPase was studied using fluorescence techniques. Fluorescence spectroscopy was combined with hydrostatic pressure to allow the study of the dissociation of the oligomeric ATPase. The erythrocyte Ca²-ATPase was shown to be a dimer with a dissociation constant (KD) between 6-9 x 10-6 M. The volume change upon dissociation was found to be approximately - 50 ml/mol. This relatively small volume change may indicate that hydrophobic interactions predominate over electrostatic interactions in the interface between the subunits. The stabilization of either the E1 ATPase conformation (by the addition of Ca²⁺) or E2 (by the addition of vanadate) favoured, respectively, the associated or the dissociated States. Calmodulin did not promote any additional effect on the dissociation over the effect promoted by Ca²⁺. The results concerning the effects of ligands on the oligomerization of the erythrocyte ATPase suggest that calmodulin does not alter the equilibrium between the two major conformational States E1 and E2. Fluorescence lifetime measurements showed that calmodulin stabilizes the enzyme in a different conformation as compared to the conformation stabilized by Ca²⁺ alone. The study of the effects of organic osmolytes on the structure and function of the erythrocyte Ca²⁺-ATPase indicated that betaine - a representative methylamine - was able to protect against the uncoupling between Ca²⁺ transport and ATP hydrolysis induced by urea. The conformational changes promoted by betaine appeared to derive from direct interactions between betaine and the ATPase. In the presence of betaine an increase in compactation of the more hydrophilic domains of the ATPase was observed. On the other hand, betaine decreased the compactation at hydrophobic internal domains of the protein, which may include the amino acids that are in contact with the phospholipids of the native membrane. Publisher: Universidade Federal do Rio de Janeiro Type: Tese Thu, 01 Oct 1992 00:00:00 GMT http://hdl.handle.net/11422/28450 1992-10-01T00:00:00Z http://hdl.handle.net/11422/28432 Title: Interação dos chamados antagonistas de calmodulina, composto 48/80 e calmidazol, nas curvas de substrato, ATP e cálcio, da (Ca²⁺+Mg²⁺)ATPase de membrana basolateral de túbulos contornados proximais Author(s)/Inventor(s): Sampaio, Tatiana Lobo Coelho de Advisor: Vieyra, Adalberto Ramon Abstract: In this work we investigated the effects of two so-callled calmodulin antagonists, compound 48/80 and calmidazolium, on the (Ca²⁺+Mg²⁺)ATPase from basolateral membranes derived from rabbit kidney proximal tubules. Analysis of the crude membrane preparation by polyacrylamide gel electrophoresis in the presence of SDS followed by incubation with anti-calmodulin antibody showed that it did not contain endogenous calmodulin. Furthermore, when the preparation was solubilized with the nonionic detergent C12E8 the (Ca²⁺+Mg²⁺)ATPase activity was stimulated by exogenous calmodulin at very low calcium concentrations (< 1 uM). This activity was inhibited 70% by compound 48/80, while it was not changed by calmidazolium. In addition, we analyzed the effects of the antagonists on the calcium and ATP concentration dependence of (Ca²⁺+Mg²⁺)ATPase activity. Compound 48/80 competitively inhibited the high-affinity ATP component, increasing Km from 0.91 to 2.41 uM. In the low-affinity component (Km = 0,87 mM), this drug promoted a linearization of the substrate curve in the range of ATP concentrations employed, giving a Vmax/Km ratio of 2.15 x 10¹ x mg-1 x min-1 . Assuming a oompetitive mechanism of inhibition, it. was possible to calculate an upper limit for Km of 16 mM. Compound 48/80 also induced the appearance of negative cooperativity (from n = 1 to n = 0.46) in the low-affinity Component. Calmidazolium reduced Vmax in both high- and low affinity components, and promoted an increase in Km only for the low-affinity site (from 0.87 to 2.54 mM). At a fixed ATP concentration (5 mM), activity increased with calcium concentration up to 10-30 uM and then decreased at higher calcium concentrations. Both drugs decreased Vmax. Compound 48/80 also decreased the calcium affinity in both low and high concentration ranges (from 2.15 to 5.72 uM and from 0.21 to 0.35 mM, respectively). The addition of Pi altered the inhibition by the two drugs in different ways. At a high ATP concentration (5 mM), Pi protected the ATPase against inhibition by compound 48/80 and potentiated the inhibition by calmidazolium. At a low ATP concentration (25 uM), Pi had no effect on the inhibition by compound 48/80, but protected against calmidazolium. In the absence of Pi, the effects of the two drugs were additives. These results suggest that compound 48/80 and calmidazolium act in different sites of the enzyme structure and, probably, by distinct mechanisms. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Thu, 01 Mar 1990 00:00:00 GMT http://hdl.handle.net/11422/28432 1990-03-01T00:00:00Z http://hdl.handle.net/11422/6661 Title: Estudo da fauna flebotomínea (Diptera: Psychodidae) na localidade de Catimbau Grande, Município de Rio Bonito - Estado do Rio de Janeiro Author(s)/Inventor(s): Almeida, Domingos Corrêa de Advisor: Brazil, Reginaldo Peçanha Abstract: In one year of research in Catimbau-Grande, Municipality of Rio Bonito, Rio de Janeiro State, the sandfly fauna was studied. Night catches using light traps and human bait were performed either in peridomestic and extradomestic environments. The richness of species found in each type of collection was estimated. Five species of the Lutzomyia genus were found: Lu. (Nyssomyia) intermedia, Lu. migonei, Lu. (Pintomyia) fischeri, Lu. (Lutzomyia) longipalpis and Lu. (Micropygomyia) schereiberi. Lu. intermedia was the most adapted specie between different levels of antropic action in the studied area. The presence of Lu. intermedia and Lu. migonei in peridomestic area showed the risk of leishmaniasis transmission, since, these species are suspect vectors of the disease in others brazilian regions. Lu. intermedia was more abundant and more antropophilic among captured species. In spite of the small number of species it was possible to elaborate a key based on the location and intensity of pigmentation of the thoracic region to separated the local species. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Mon, 01 Jan 1996 00:00:00 GMT http://hdl.handle.net/11422/6661 1996-01-01T00:00:00Z http://hdl.handle.net/11422/3604 Title: Mobilização rápida de citocromo-oxidase por estimulação sensorial em córtex visual de gatos e primatas Author(s)/Inventor(s): Ribeiro, Sidarta Tollendal Gomes Advisor: Gattass, Ricardo Abstract: The cytochrome oxidase fast mobilization was studied in twelve cats (Felis catus) and three monkeys (Cebus apella). Visual stimulus of low spatial frequency, with variations in colour and brightness and no spatial orientation allowed the observation of cytochrome oxidase-rich patches in flattened sections of cat's visual cortex. The patches appeared in Vl, V2 and V3 supragranular layers, as well as in other extra-striated areas. Morphologically, those patches are equivalent to the blobs recently described in cat by improved histochemical methods. The morphometric analysis reveals that blobs medium size tend to increase from Vl to V2 and from V2 to V3. The densitometric analysis of monocularly stimulated monkey' s striate cortex sections shows a cytochrome-oxidase activation peak after thirty minutes of stimulation, followed by a decrease in optical density at greater times. This indicates that the phenomena is composed of two distinct phases. The monocular stimulation by stroboscopic light shows ocular dominance columns in monkey's Vl after thirty minutes. The cytochrome oxidase fast mobilization phenomena may be the product of the immediate activation of one or more genes of the enzyme' s subunits, of allosteric interactions with ATP, or of local redistribution of mitochondria. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Thu, 01 Dec 1994 00:00:00 GMT http://hdl.handle.net/11422/3604 1994-12-01T00:00:00Z