Concise synthesis of the pentasaccharide O-antigen of Escherichia coli O83:K24:H31 present in the Colinfant vaccine

A block synthetic approach is presented for the synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O83:K24:H31 strain, present in the “Colifant” vaccine. The target pentasaccharide has been synthesized by coupling a disaccharide with a trisaccharide in excellent yield. Yields are quite satisfactory in all intermediate steps. A concise synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O83:K24:H31 strain, present in the COLINFANT vaccine is presented. The target pentasaccharide has been synthesized following a block synthetic strategy by coupling a disaccharide with a trisaccharide in excellent yield.     

Sustained Release of a Water-Soluble Drug from Alginate Matrix Tablets Prepared by Wet Granulation Method

Alginate matrix tablet of diltiazem hydrochloride (DTZ), a water-soluble drug, was prepared using sodium alginate (SAL) and calcium gluconate (CG) by the conventional wet granulation method for sustained release of the drug. The effect of formulation variables like SAL/CG ratio, drug load, microenvironmental pH modulator, and processing variable like compression force on the extent of drug release was examined. The tablets prepared with 1:2 w/w ratio of SAL/CG produced the most sustained release of the drug extending up to 13.5 h. Above and below this ratio, the drug release was faster. The drug load and the hardness of the tablets produced minimal variation in drug release. The addition of alkaline or acidic microenvironmental modulators did not extend the release; instead, these excipients produced somewhat faster release of diltiazem. This study revealed that proper selection of SAL/CG ratio is important to produce alginate matrix tablet by wet granulation method for sustained release of DTZ.     

Chromogranin A-derived peptides: interaction with the rat posterior cerebral artery

Chromogranin A (CgA), an acidic granule protein of the regulated secretory pathway in the diffuse neuroendocrine system, is postulated to serve as a prohormone for regulatory peptides. Betagranin (rCgA(1-128)), the first N-terminal cleavage product of rat CgA, is 87% homologous to the bovine vasostatin I (bCgA(1-76)), previously shown to be vasoinhibitory in bovine resistance arteries. In this study the vasoactivity of homologous rat and bovine peptides was investigated in the rat posterior cerebral artery. Firstly, we examined the interaction of rhodamine (Rh)-labelled bCgA(7-40) and bCgA(47-70) with elements of the arterial wall by fluorescence microscopy. Secondly, rCgA(7-57), bCgA(1-40), bCgA(7-40) and bCgA(47-66) (chromofungin) were studied for effects on arterial tone and intracellular calcium as function of pressure in an arteriograph. Although without dilator or constrictor responses at 60-150 mm Hg, the rat peptide (rCgA(7-57)) evoked a significant delay in the onset of forced dilatation at 170 mm Hg, in contrast to the bovine peptides bCgA(1-40), bCgA(7-40) and bCgA(47-66) (chromofungin). Neither Rh-bCgA(7-40) nor Rh-bCgA(47-70) stained the endothelial layer, while Rh-bCgA(47-70) but not Rh-bCgA(7-40) stained the smooth muscle compartment. Analogously, bCgA(47-66) but not bCgA(7-40) reduced intracellular calcium, however without modifying the myogenic response. Thus, the betagranin peptide rCgA(7-57) and the two bovine chromofungin-containing peptides, highly homologous to the corresponding sequence (rCgA(47-66)), affected the rat cerebral artery without vasodilator effects, indicating significant species differences in vasoactivity of the N-terminal domain of CgA.     

Comparative Analysis of GS2 and Fd-GOGAT Genes in Cultivated Wheat and Their Progenitors Under N Stress

Plant Molecular Biology Reporter - Polyploidization plays an important role in the genesis of cultivated wheat (hexaploid and tetraploid) from its diploid progenitors. Thus, evolution during...     

Catalytic phosphorylation of Na,K-ATPase drives the outward movement of its cation-binding H5-H6 hairpin

The Na,K-ATPase undergoes conformational transitions during its catalytic cycle that mediate energy transduction between the phosphorylation and cation-binding sites. Structure-function studies have shown that transmembrane segments H5 and H6 in the alpha subunit of the enzyme participate in cation binding and transport. The Ca-ATPase crystal structure indicates that the H5 helix extends into the cytoplasmic ATP binding domain, finishing 4-5 A from the phosphorylation site. Here, we test whether the phosphorylation of the Na,K-ATPase leads to conformational changes in the cation-binding H5-H6 hairpin. Using as background an enzyme where all wild-type Cys in the transmembrane region were replaced, Cys were introduced in the joining loop and extracellular ends of H5 and H6. Mutated proteins were expressed in COS cells and probed with Hg(2+), [2-(trimethylammonium)ethyl]methanethiosulfonate (MTSET), and biotin-maleimide, applied to the extracellular media while placing the cells in two different media (K-medium and Na-medium). We assumed that under these treatment conditions most of the enzyme would be in one of two predominant conformations: E1 (K-medium) and E2P (Na-medium). The extent of enzyme inactivation by Hg(2+) or MTSET treatment was dependent on the targeted position; i.e., proteins carrying Cys in the outermost positions were more affected by treatment. Moreover, in the case of proteins carrying Cys at positions 785, 787, and 797, driving the enzyme to phosphorylated conformations (Na-media) led to a larger inactivation. Similarly, biotinylation of introduced Cys was also influenced by the enzyme conformation, with a larger extent of modification after treatment of cells in the Na-medium (E2P form). These results can be explained by the enzyme phosphorylation driving the outward movement of the H5 helix. Thus, they provide experimental evidence for a structure-function mechanism where, via H5, enzyme phosphorylation leads to a conformational change at the cation-binding site and the consequent cation translocation.     

Development of a series of novel o-phenylenediamine-based indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors

A novel series of o-phenylenediamine-based inhibitors of indoleamine 2,3-dioxygenase (IDO) has been identified. IDO is a heme-containing enzyme, overexpressed in the tumor microenvironment of many cancers, which can contribute to the suppression of the host immune system. Synthetic modifications to a previously described diarylether series resulted in an additional degree of molecular diversity which was exploited to afford compounds that demonstrated significant potency in the HeLa human cervical cancer IDO1 assay..