Automated chloridite and amidite synthesis of oligodeoxyribonucleotides on a long chain support using amidine protected purine nucleosides

1989 ◽  
Vol 54 (2) ◽  
pp. 523-532 ◽  
Author(s):  
Luboš Arnold ◽  
Zdeněk Točík ◽  
Eliška Bradková ◽  
Zdeněk Hostomský ◽  
Václav Pačes ◽  
...  
Keyword(s):  
Automated Synthesis ◽  
Oligonucleotide Synthesis ◽  
Potassium Salts ◽  
Solid Supports ◽  
Ethanol Precipitation ◽  
Aliphatic Spacer ◽  
Long Chain

Preparation of solid supports with long aliphatic spacer for the oligonucleotide synthesis is described. Automated synthesis of oligodeoxyribonucleotides using in situ prepared methylchlorophosphite intermediates from amidine protected purine nucleosides is described. Phosphoramidite synthesis of oligodeoxyribonucleotides mediated by 1-methylimidazole trifluoromethanesulfonate is described. Novel isolation of crude oligonucleotides by ethanol precipitation of potassium salts is described.

Biophysics (and sociology) of ceramides.

2005 ◽  
Vol 72 ◽  
pp. 177-188 ◽  
Author(s):  
Félix M. Goñi ◽  
F-Xabier Contreras ◽  
L-Ruth Montes ◽  
Jesús Sot ◽  
Alicia Alonso
Keyword(s):  
Cell Biology ◽  
Positive Curvature ◽  
Acyl Chain ◽  
Cell Signalling ◽  
Hexagonal Structure ◽  
Lipid Monolayer ◽  
Flip Flop ◽  
Long Chain ◽  
Bilayer Permeability

In the past decade, the long-neglected ceramides (N-acylsphingosines) have become one of the most attractive lipid molecules in molecular cell biology, because of their involvement in essential structures (stratum corneum) and processes (cell signalling). Most natural ceramides have a long (16-24 C atoms) N-acyl chain, but short N-acyl chain ceramides (two to six C atoms) also exist in Nature, apart from being extensively used in experimentation, because they can be dispersed easily in water. Long-chain ceramides are among the most hydrophobic molecules in Nature, they are totally insoluble in water and they hardly mix with phospholipids in membranes, giving rise to ceramide-enriched domains. In situ enzymic generation, or external addition, of long-chain ceramides in membranes has at least three important effects: (i) the lipid monolayer tendency to adopt a negative curvature, e.g. through a transition to an inverted hexagonal structure, is increased, (ii) bilayer permeability to aqueous solutes is notoriously enhanced, and (iii) transbilayer (flip-flop) lipid motion is promoted. Short-chain ceramides mix much better with phospholipids, promote a positive curvature in lipid monolayers, and their capacities to increase bilayer permeability or transbilayer motion are very low or non-existent.

Composite Magnetic and Non-magnetic Beads as Efficient Solid Supports for Machine-Aided Oligonucleotide Synthesis

2001 ◽  
Vol 84 (2) ◽  
pp. 345-350 ◽  
Author(s):  
Pradeep Kumar ◽  
Ashwani K. Sharma ◽  
Kailash C. Gupta ◽  
Shlomo Margel ◽  
Sigalit Gura ◽  
...  
Keyword(s):  
Magnetic Beads ◽  
Oligonucleotide Synthesis ◽  
Solid Supports

scholarly journals In situ ozonolysis of polypropylene during extrusion to produce long-chain branches with the aid of TMPTA

RSC Advances ◽  
2017 ◽  
Vol 7 (36) ◽  
pp. 22531-22539 ◽  
Author(s):  
Guang-Jian He ◽  
Bing-Yu Yuan ◽  
Ting-Ting Zheng ◽  
Wen-li Zhu ◽  
Xiao-Chun Yin
Keyword(s):  
Extrusion Process ◽  
Secondary Products ◽  
Long Chain

The introduction of long-chain branches (LCBs) in polypropylene (PP) during the extrusion process is normally induced by peroxide chemicals which are known to cause to the formation of secondary products in the resin.

scholarly journals Extraction and Characterization of Inulin-Type Fructans from Artichoke Wastes and Their Effect on the Growth of Intestinal Bacteria Associated with Health

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Zahraa Zeaiter ◽  
Maria Elena Regonesi ◽  
Sofia Cavini ◽  
Massimo Labra ◽  
Guido Sello ◽  
...  
Keyword(s):  
Intestinal Bacteria ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Globe Artichoke ◽  
Ethanol Precipitation ◽  
Long Chain ◽  
Simpler Method

Globe artichoke is an intriguing source of indigestible sugar polymers such as inulin-type fructans. In this study, the effect of ultrasound in combination with ethanol precipitation to enhance the extraction of long chain fructans from artichoke wastes has been evaluated. The inulin-type fructans content both from bracts and stems was measured using an enzymatic fructanase-based assay, while its average degree of polymerization (DP) was determined by HPLC-RID analysis. Results show that this method provides artichoke extracts with an inulin-type fructans content of 70% with an average DP between 32 and 42 both in bracts and in stems. The prebiotic effect of long chain inulins from artichoke extract wastes was demonstrated by its ability to support the growth of five Lactobacillus and four Bifidobacterium species, previously characterized as probiotics. Besides, we considered the possibility to industrialize the process developing a simpler method for the production of inulin-type fructans from the artichoke wastes so that the artichoke inulin preparation could be suitable for its use in synbiotic formulations in combination with different probiotics for further studies including in vivo trials.

scholarly journals Delaminated Polymer/Lamellar Aluminophosphate Nanocomposites Prepared via in SITU Polymerization

2006 ◽  
Vol 15 (5) ◽  
pp. 096369350601500 ◽  
Author(s):  
Jingyu Wang ◽  
Guoping Chen ◽  
Quan Zhou
Keyword(s):  
Polymer Matrix ◽  
In Situ Polymerization ◽  
Short Chain ◽  
Long Chain

A method to synthesize completely delaminated polymer/lamellar aluminophosphate (Mu-4) nanocomposites has been successfully developed, wherein organo-modification of Mu-4 followed by in situ polymerization was applied. It can be found that the long chain n-dodecylamine molecules can favor the intercalation of Mu-4 and thus readily make the Mu-4 layers delaminated in the polymer matrix compared with the short chain N,N-dimethylpropane-1,3-diamine.

2-(3-Acylselenoureido)benzonitriles and 2-(3-Acylselenoureido)thiophene-3-carbonitriles. Preparation, Structure Elucidation, Cyclization and Retrocyclization Reactions

1999 ◽  
Vol 64 (10) ◽  
pp. 1673-1695 ◽  
Author(s):  
Jiří Šibor ◽  
Dalimil Žůrek ◽  
Radek Marek ◽  
Michal Kutý ◽  
Otakar Humpa ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Quantum Chemistry Calculation ◽  
Potassium Salts ◽  
X Ray ◽  
Chemistry Calculation ◽  
Acid Cyclization

Synthesis of 2-(3-acylselenoureido)benzonitriles and 2-(3-acylselenoureido)thiophene- 3-carbonitriles 5a-5f by addition of 2-aminonitriles 4a-4c to benzoyl- or 2,2-dimethyl- propanoylisoselenocyanate and their cycloaddition reactions are described. Structures of compounds 5a-5f were supported by CIMS, FTIR, 1H, 13C, 77Se and 15N NMR spectra. The parameters of 15N and 77Se nuclei were obtained from inverse 1H-X 2D HMBC and GSQMBC correlation experiments at natural abundance. Structure of compound 5b was confirmed by X-ray analysis. The geometry of 5b was optimized by ab initio RHF/DZVP quantum chemistry calculation. A very good correlation between the calculation and experimental data was found. The geometry of 5e was optimized by ab initio DFT/VWN/DZVP quantum chemistry calculation. It was found that title compounds 5a-5f do not undergo isomerization to acylisoselenoureas, in contrast to analogous ester derivatives. Fused 6-imino-6H-1,3- selenazinium salts (chlorides 6a-6f, hydrogensulfates 7a-7f and tetrafluoroborates 8a-8f) were prepared by an acid cyclization of 5a-5f. It was found that neutralization of 6a-6f, 7a-7f and 8a-8f led to their retrocyclization to 5a-5f. Selenoureas 5a-5f with equimolar amounts of methanolic potassium hydroxide afforded potassium salts 9a-9f. Only the salts 9b, 9c, 9e and 9f of the thiophene series were isolated. Their heating in methanol solution led to deacylation of isoselenoureas 10b and 10c. The in situ prepared compounds 9a and 9d cyclized and deacylated to 4-aminoquinazoline-2-selenole 11a under the same conditions. The compounds 5a-5f and 10a-10c cyclized to fused 4-aminopyrimidine-2-selenols 11a, 11b and 4-aminopyrimidine-2-selenone 12c by boiling in methanolic potassium hydroxide solution.

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