ABSTRACT
An efficient synthesis of 2'-O-substituted ribonucleosides, including 2'-O-TBDMS and 2'-O-TOM protected as well as 2'-O-Me and 2'-O-allyl derivatives is presented. Di-t-butylsilylene group was employed for simultaneous protection of 3'- and 5'- hydroxyl functions of nucleoside on the first step. Subsequent silylation or alkylation of free 2'-OH followed by introduction of suitable protection on the base moiety and removal of cyclic silyl protection gave target compounds in a high yield.
Subject(s)
Ribonucleosides/chemical synthesis , Alkylation , Indicators and Reagents , Methylation , Models, Molecular , Molecular Structure , Organosilicon Compounds , Structure-Activity RelationshipABSTRACT
1,2-Dideoxyribose 5-O-succinate, a component of solid support employed in the synthesis of ribozymes, was synthesized from thymidine. The key step was elimination of nucleobase from 2 to afford glycal 3. A number of catalysts for this reaction were tested, resulting in improved and scaleable synthesis. Hydrogenation of the resulting glycal afforded 1,2-dideoxyribose derivative 4 in a high yield.
Subject(s)
Deoxyribose/analogs & derivatives , Thymidine/analogs & derivatives , Thymidine/chemical synthesis , Indicators and Reagents , Molecular ConformationABSTRACT
Recombinant endo-beta-1,4-xylanase (Xyl-31rec, 31 kD, pI 8.2-9.3, the tenth family of glycosyl hydrolases) was isolated from the culture liquid of Penicillium canescens (strain with the amplified homologous xylanase gene) by chromatofocusing on Mono P and hydrophobic chromatography on phenyl-Superose. It is shown that the biochemical and kinetic parameters, substrate specificity, stability, and other properties of the recombinant and native enzymes are almost the same. It was found that Xyl-31rec can be used for biobleaching of cellulose, the recombinant P. canescens strains providing a high yield of extracellular Xyl-31rec (up to 800-900 U/ml of culture liquid) and not secreting cellulases.
Subject(s)
Endo-1,4-beta Xylanases/genetics , Endo-1,4-beta Xylanases/metabolism , Penicillium/enzymology , Recombinant Proteins/metabolism , Absorption , Cellulose/metabolism , Chromatography , Endo-1,4-beta Xylanases/isolation & purification , Enzyme Stability , Hydrogen-Ion Concentration , Penicillium/genetics , Recombinant Proteins/genetics , Recombinant Proteins/isolation & purification , Substrate Specificity , TemperatureABSTRACT
The remarkable carcinogenic activity of 6-nitrochrysene (6-NC) in several animal models, and its environmental presence, suggest its potential importance with regard to human cancer development. Depending on the bioassay model, 6-NC can be activated by simple nitro reduction, ring oxidation, or by a combination of ring oxidation and nitro reduction. Only the first pathway has been clearly established. Thus, this study purports to unequivocally define the other pathways. Toward this end, we report for the first time the synthesis of anti-1,2-dihydroxy-3,4-epoxy-1,2,3, 4-tetrahydro-6-nitrochrysene (6-NCDE), a likely ultimate carcinogenic metabolite of 6-NC. Also, we describe our initial investigation of its binding with calf thymus DNA, 2'-deoxyguanosine-5'-monophosphate (2'-dGuo), and 2'-deoxyadenosine-5'-monophosphate (2'-dAdo) in vitro. These adduct markers were then employed for comparison with those obtained in the rat after in vivo treatment with 6-NC. On the basis of the results, it appears that the major adduct formed in the liver of rats treated with 6-NC is not derived from 6-NCDE.
