A new bromine-containing reagent for cysteine modification

5-Bromo-2[(2-iodoacetyl)amino]benzenesulfonic acid (AIBSA), a reagent for modification of free of cysteine thiol groups in proteins and peptides, was synthesized. Rate constants of its interaction with thiol groups were determined. The presence of a bromine atom allows an easy identification of the AIBSA-labeled peptides in mass spectra due to the characteristic isotope distribution. The compound is stable in solution and under exposure to light.     

Ultrastructure of diatom <Emphasis Type="Italic">Synedra acus</Emphasis> subsp. <Emphasis Type="Italic">radians</Emphasis> as revealed by transmission electron microscopy after mild silica dissolution

A diatom Synedra acus subsp. radians (Kotz.) Skabitsch. has been studied by transmission electron microscopy. Examination of ultrathin sections demonstrated that silica dissolution in ammonium fluoride pH 5 under mild conditions leaves the key ultrastructural elements intact. The ultrastructure and arrangement of the cell organelles was studied during ontogeny. Silicalemma-surrounded silica deposition vesicles (SDVs) with maturating daughter valves and forming girdle bands have been identified. This method of SDV visualization offers considerable advantages over the standard approach without silica dissolution.     

Computation techniques in the conformational analysis of carbohydrates

A growing number of modern studies of carbohydrates is devoted to spatial mechanisms of their participation in the cell recognition processes and directed design of inhibitors of these processes. No progress in this field is possible without the development of theoretical conformational analysis of carbohydrates. In this review, we generalize literature data on the potentialities of using various molecular-mechanic force fields, the methods of quantum mechanics, and molecular dynamics to study the conformation of glycoside linkage. A possibility of analyzing the reactivity of carbohydrates with the computation techniques is also discussed in brief.     

Fungicidal activity of cellobiose lipids from culture broth of yeast <Emphasis Type="Italic">Cryptococcus humicola</Emphasis> and <Emphasis Type="Italic">Pseudozyma fusiformata</Emphasis>

Cellobiose lipids of yeast fungi Cryptococcus huminola and Pseudozyma fusiformata have similar fungicidal activities against different yeast, including pathogenic Cryptococcus and Candida species. Basidiomycetic yeast reveals maximum sensitivity to these preparations; e.g., cells of cryptococcus Filobasidiella neoformans almost completely die after 30-min incubation in a glycolipid solution at a concentration of 0.02 mg/ml. The same effect toward ascomycetous yeast, including pathogenic Candida species, is achieved only at five to eight times higher concentrations of glycolipids. The cellobiose lipid from P. fusiformata, which, unlike glycolipid from Cr. humicola, has hydroxycaproic acid residue as O-subtituent of cellobiose and additional 15-hydroxy group in aglycone, inhibits the growth of the studied mycelial fungi more efficiently than the cellobiose lipid from Cr. humicola.     

Effect of the tissue architecture on cell-to-cell calcium signaling

A novel approach based on the approximation of tissue structure by the Voronoi diagram has been elaborated to study cell-to-cell signaling in a tissue mediated by gap junctions. This methodology was applied for the analysis of Ca2+ signaling in the airway epithelium, where adjacent cells were taken to be coupled by gap junctions whose permeability depended on Ca2+ concentration in their cytoplasm. The number of junctional channels connecting a given pair of cells was postulated to be directly proportional to the length of the boundary between them. In a certain range of parameters, a modeled cell generate intracellular Ca2+ oscillations upon the stimulation with the purinergic agonist ATP, and the Ca2+ signal propagated through the tissue due to a Ca2+ rise in adjacent connected cells. The influence of variable sensitivity of cells to ATP on Ca2+ signaling in the tissue was also examined. The model also showed that a mechanical disturbance of a single airway epithelial cell resulted in a prolonged increase in Ca2+ concentration in its cytoplasm, which entailed the spreading of a Ca2+ wave along the tissue.     

<Emphasis Type="Italic">N</Emphasis>-azidomethylbenzoyl blocking group in the phosphotriester synthesis of oligoribonucleotides

An effective modification of the phosphotriester method has been developed for the automatic synthesis of DNA and RNA fragments using O-nucleophilic intramolecular catalysis and the 2-(azidomethyl)benzoyl group for the protection of the amino groups of nucleotide heterocyclic bases.