Paulo F. F. Almeida

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In the current understanding of exocytosis at the nerve terminal, the C2 domain of synaptotagmin (C2A) is presumed to bind Ca2+ and the membrane in a stepwise fashion: cation then membrane as cation increases the affinity of protein for membrane. Fluorescence spectroscopy data were gathered over a variety of lipid and Ca2+ concentrations, enabling the(More)
We have recently proposed a phase diagram for mixtures of porcine brain sphingomyelin (BSM), cholesterol (Chol), and 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) on the basis of kinetics of carboxyfluorescein efflux induced by the amphipathic peptide delta-lysin. Although that study indicated the existence of domains, phase separations in the micrometer(More)
This paper describes a traffic surveillance system as a particular case of the class of intelligent distributed dynamic-information systems (IDDIS). The Traffic Surveillance System is a vision-based FIPA compliant multi-agent system that uses the FIPA Agent Communication Language (ACL) and the FIPA Semantic Language (SL). The focus of the work is(More)
The kinetics and thermodynamics of binding of transportan 10 (tp10) and four of its variants to phospholipid vesicles, and the kinetics of peptide-induced dye efflux, were compared. Tp10 is a 21-residue, amphipathic, cationic, cell-penetrating peptide similar to helical antimicrobial peptides. The tp10 variants examined include amidated and free peptides,(More)
In the current understanding of exocytosis at the nerve terminal, the C2A domain of synaptotagmin is presumed to bind Ca 2+ and the membrane in a stepwise fashion: cation then membrane as cation increases the affinity of protein for membrane. Fluorescence spectroscopy data was gathered over a variety of lipid and Ca 2+ concentrations, enabling the rigorous(More)
The ability of amphipathic polypeptides with substantial net positive charges to translocate across lipid membranes is a fundamental problem in physical biochemistry. These peptides should not passively cross the bilayer nonpolar region, but they do. Here we present a method to measure peptide translocation and test it on three representative(More)
The first quantitative insight has been obtained into the effects that volatile anesthetics have on the interactions and lateral organization of lipids in model membranes that mimic "lipid rafts". Specifically, nearest-neighbor recogntion measurements, in combination with Monte Carlo simulations, have been used to investigate the action of isoflurane,(More)
One of the long-standing issues surrounding cholesterol (Chol) relates to its two-faced character. In particular, the consequences of its having a rough β-face and a smooth α-face on its structural influence in cell membranes has remained elusive. In this study, direct comparisons have been made between cholesterol and a "smoothened" analog, DChol (i.e.,(More)
Understanding the mechanisms of antimicrobial, cytolytic and cell-penetrating peptides is important for the design of new peptides to be used as cargo-delivery systems or antimicrobials. But these peptides should not be hemolytic. Recently, we designed a series of such membrane-active peptides and tested several hypotheses about their mechanisms on model(More)
Antimicrobial, cytolytic, and cell-penetrating peptides induce pores or perturbations in phospholipid membranes that result in fluxes of dyes into or out of lipid vesicles. Here we examine the fluxes induced by four of these membrane-active peptides in giant unilamellar vesicles. The type of flux is determined from the modality of the distributions of(More)