Ribonucleic acid polymerase from eukaryotic cells: effects of factors and rifampicin on the activity of RNA polymerase from chromatin of coconut nuclei

The role of protein factor B and C on RNA synthesis by RNA polymerase CI isolated from chromosomal non-histone proteins of coconut nuclei has been studied further. Factor B has been implicated as the initiation factor on the experimental evidences that (a) in its absence, RNA polymerase CI shows only minimal activity; (b) it can bind with RNA polymerase and the enzyme . factor B complex then binds to DNA, but factor B alone can not bind to DNA; (c) it promotes the incorporation of [β,-32P2]ATP into RNA and this stimulation reaches a plateau rather quickly while the incorporation of [14C]ATP in the interior of RNA chain continues; (d) it is active with native homologous DNA as template, but not with denatured or λ DNA; (e) RNA molecules synthesized in its presence are of higher sedimentation value (10-20 S) than that synthesized in its absence (4 S); (f) it can completely counteract the inhibitory effect of rifampicin, which is known to inhibit RNA synthesis at the initiation step. Factor C seems to facilitate the release of synthesized RNA from the DNA template since (a) it stimulates RNA synthesis by polymerase CI when added on top of factor B, but in absence of factor B, C alone is inactive; (b) it can reinitiate RNA synthesis after the reaction has reached a plateau in a system where DNA is limiting, an affect similar to that obtained at higher ionic strength. Factor C, however, does not influence the molecular size of RNA synthesized. Furthermore, the RNA polymerase CI is sensitive to α-amanitin whereas the RNA polymerase CII is comparatively resistant. The former appears to synthesize the non-ribosomal RNA whereas the latter synthesizes ribosomal RNA

A Rapid, Efficient and Green Method for Synthesis of 3,3'-Arylmethylene-bis-4-hydroxycoumarins without Use of any Solvent, Catalyst or Solid Surface

Abstract: A rapid, efficient and green methodology has been developed for the synthesis of 3,3'-arylmethylene-bis-4-hydroxycoumarins by microwave assisted condensation of aromatic aldehydes and 4-hydroxycoumarin without use of any solvent, catalyst or solid surface

An Expeditious and Safe Synthesis of Some Exocyclic α,β-Unsaturated Ketones by Microwave-Assisted Condensation of Cyclic Ketones with Aromatic Aldehydes over Anhydrous Potassium Carbonate

A rapid, efficient, and solvent-free methodology for synthesis of exocyclic α,β-unsaturated ketones of the categories E-3-arylidene-4-chromanones, E-2-arylidene-1-tetralones, E-2-arylidene-1-indanones, E-3-cinnamylidene-4-chromanones, E-2-cinnamylidene-1-tetralones, E-2-cinnamylidene-1-indanones, α,α′-(E,E)-bis(arylidene)-cycloalkanones, and α,α′-(E,E)-bis(cinnamylidene)-cycloalkanones has been developed through cross-aldol condensation of the constituent cyclic ketones and aldehydes by microwave irradiation over anhydrous potassium carbonate. However, for condensation of 1-thio-4-chromanones with aromatic aldehydes by this method, the initially formed exocyclic α,β-unsaturated ketone has been found to undergo isomerization yielding 3-(arylmethyl)thiochromones

(E)-2-(2-Pyridinyl)-3-(2-pyridinylmethylene)chromanone, a 1:2 condensation product of 2′-hydroxyacetophenone and pyridine-2-aldehyde, showing some interesting properties

805-810An efficient synthesis of (E)-2-(2-pyridinyl)-3-(2-pyridinylmethylene)chromanone has been done by treatment of 2′-hydroxyacetophenone and pyridine-2-aldehyde in aqueous methanolic KOH. The compound has been obtained as crystalline precipitate from the reaction medium, which was suitable for spectral analysis and X-ray crystallographic study. It possesses an interesting intramolecular hydrogen bonding between the C2-H and the nitrogen of 2-pyridinylmethylene moiety. At room temperature, it is stable for months in the crystalline state, but in CDCl3 solution it gradually changes to the endocyclic isomer 2-(2-pyridinyl)-3-(2-pyridinylmethyl)chromone. From analysis of the X-ray crystallographic data and DFT studies, possible explanations have been given for the stability of the compound in the crystalline state and its isomerization in solution

Facile Condensation of Aromatic Aldehydes with Chroman-4-ones and 1-Thiochroman-4-ones Catalysed by Amberlyst-15 under Microwave Irradiation Condition

Different aromatic aldehydes and cinnamaldehyde undergo cross-aldol condensation with chroman-4-ones and1-thiochroman-4-ones in the presence of amberlyst-15 under microwave irradiation in solvent free condition to afford rapidly the corresponding E-3-arylidene and E-3-cinnamylidene derivatives, respectively, in high yield. This process is simple, efficient and environmentally benign

Schmidt Reaction of E-3-Benzylidenechromanones and E-3-Benzylidenethiochromanones

On treatment with NaN3/c. H2SO4-HOAc or NaN3/TFA, E-3-benzylidenechromanones are mostly converted to E-β-aminobenzylidenechromanones while E-3-benzylidenethiochromanones are converted to 3-benzoylthiochromones. A structurally new type of product has been isolated for the reaction of E-3-benzylidene-4′-methoxychromanone with NaN3/TFA. Mechanistic paths have been suggested for formation of the products

Synthesis of several types of 2,8-dioxabicyclo[3.3.1]nonanes using amberlyst-15 as an efficient recyclable heterogeneous catalyst

<p>A facile synthesis of 2,8-dioxabicyclo[3.3.1]nonane derivatives starting from simple molecules like 2-hydroxychalcones as one component and dimedone, 4-hydroxycoumarin, 2-hydroxynaphthoquinone, 2-naphthol or 1-naphthol, as the other has been achieved by use of amberlyst-15, a sulfonated polystyrene resin, as a recyclable heterogeneous catalyst. The methodology involves a domino sequence of Michael addition and two-stage cyclisation.</p