Dikeos Mario Soumpasis

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We derive an exact closed formula for the fluorescence recovery curve measured in fluorescence photobleaching recovery experiments employing uniform circular laser beams. In contrast to the expression used currently, this result is very simple and free of mathematical drawbacks, thus facilitating the quantitative analysis of experimental data.
All eukaryotic sialyltransferases have in common the presence in their catalytic domain of several conserved peptide regions (sialylmotifs L, S, and VS). Functional analysis of sialylmotifs L and S previously demonstrated their involvement in the binding of donor and acceptor substrates. The region comprised between the sialylmotifs S and VS contains a(More)
We examined more than 700 DNA sequences (full length chromosomes and plasmids) for stretches of purines (R) or pyrimidines (Y) and alternating YR stretches; such regions will likely adopt structures which are different from the canonical B-form. Since one turn of the DNA helix is roughly 10 bp, we measured the fraction of each genome which contains purine(More)
A theoretical framework is constructed to treat the effects of salt ions on polyionic structural transitions in the absence of specific ion binding. As an application, the salt concentration-dependent part of the free energy difference governing the B----ZI transition of [d(C-G) . d(C-G)]6 in 1:1 electrolytes is calculated; quantitative agreement with the(More)
We present a statistical mechanical description of biomolecular hydration that accurately describes the hydrophobic and hydrophilic hydration of a model alpha-helical peptide. The local density of water molecules around a biomolecule is obtained by means of a potential-of-mean-force (PMF) expansion in terms of pair- and triplet-correlation functions of bulk(More)
We have studied the B-Z transition of poly[d(G-C)] in the presence of alkali metal, tetramethylammonium and tetraethylammonium chlorides at room temperature. The measured critical salt concentrations increase in the order Na, K, Rb, TMA, Cs and are in good agreement with the theoretical values predicted from a statistical-mechanical treatment of the(More)
Curved DNA structures can be either intrinsic or induced through interaction with proteins. Large DNA molecules can adopt complex curved shapes in space. Many curved DNA structures (e.g., Cro-operator, Cap-operator, nucleosomal DNA, etc.) are believed to have important biological functions. To model curved DNA molecules is a challenging task. In this work,(More)
Human erythrocytes were incubated in isotonic solutions of different monovalent cations. The apparent size of the red cells measured on scanning electron microscopic pictures decreases in the order Li+>Na+=K+>Rb+. These differences in size are abolished after pretreatment with trypsin, which removes a large part of the charges associated with membrane(More)
The electrostatics of a simple membrane model picturing a lipid bilayer as a low dielectric constant slab immersed in a homogeneous medium of high dielectric constant (water) can be accurately computed using the exact Green's functions obtainable for this geometry. We present an extensive discussion of the analysis and numerical aspects of the problem and(More)