Instrumentation engineering and science Measurement devices pressure, temperature, flow, voltage, frequency etc.
SRJ is a prestige metric based on the idea that not all citations are the same. SJR uses a similar algorithm as the Google page rank; it provides a quantitative and qualitative measure of the journal's impact. SNIP measures contextual citation impact by wighting citations based on the total number of citations in a subject field. These novel monomers have been synthesized by the incorporation of thiol moiety in the side chain of peptide nucleic acid backbone.
It was recently found in lieu of finding relationship of PNA to the origin of life that PNA-like materials are present in cyanobacteria Banack et al.
PNA probes are very sequence-selective and advanced to DNA probes in single-base mismatch recognition. As enzymes are substrate specific, the recognition of neutral backbone of PNA is not easy by either nucleases or proteases, making them potentially resistant to enzymatic degradation and their stability over wide pH range. The major drawbacks like poor water solubility, inefficient cellular uptake, self-aggregation and ambiguity in directionality of binding restricts its applications within medicine, diagnostics, molecular biology, etc.
One approach to improve cellular uptake is to conjugate PNAs to a wide variety of ligands, such as artificial nucleases, peptides, intercalators or fluorescent reporter groups in order to combine the favourable properties of both entities in a single construct. In most of these conjugates, the attachment of ligand is either to the C - or N -terminal end of the PNA. Over the years, a number of backbone-modified PNAs have been prepared to study the effect of introducing chirality, charge or steric bulk on their properties such as hybridization or solubility.
The application of a suitably protected thiol modified PNA monomer would give access to a PNA oligomer containing a sulfhydryl group suitable for post-assembly conjugation methods De Koning et al. Melting points were determined on a sulphuric acid bath and are uncorrected.
Analytical TLCs were performed on pre-coated Merck silica gel 60F plates with fluorescence indicator; the spots were detected by viewing under UV light or by iodine chamber. Column chromatography was carried out using silica gel — mesh.
All other chemicals used were purchased either from S. A solution of 4-methoxybenzyl chloride 5. The reaction mixture was stirred for 2 h at room temperature. Then methanol mL and water mL were added, the layers were separated and the organic layer was re-extracted with water mL. The aqueous layer was washed with DCM, filtered and solvents were removed in vacuo. The reaction mixture was stirred for 3 h at room temperature.
Methanol was then evaporated and the residue was washed with diethyl ether. Benzyloxycarbonyl chloride 5. The mixture was stirred overnight and, subsequently, the pyridine suspension was evaporated to dryness. The resultant white precipitate was filtered off, washed with water and partially dried. Ethyl bromoacetate 0. The reaction mixture was stirred overnight at room temperature. The solution was then filtered and evaporated to dryness. The solid residue was treated with water 4 mL and 4 M HCl 0.
Water 2. The compound was precipitated by the addition of 4 M HCl 2 mL. Hydroxybenzotriazole 7 g, The solution was poured into water mL and then filtered. The organic layer was dried with Na 2 SO 4 , filtered and evaporated to a small volume. A solution of [ methoxymethylcarbamoyl -methyl]-carbamic acid tert-butyl ester 3 g, The solution was dried on Na 2 SO 4 and the solvent was then evaporated to yield crude aldehyde.
The aldehyde 2 g, Methanol was evaporated and then the residue was dissolved in ethyl acetate. The reaction mixture was stirred overnight and then added to ice cold water 10 mL. The reaction mixture was stirred overnight and then methanol was evaporated.
The mixture was acidified to pH 5 by the addition of 2 M HCl solution. The precipitate was then filtered and washed with ether. The chiral centre of cysteine, i. Synthesis of S - p -Methoxybenzyl cysteine methylester hydrochloride. The final steps to the target PNA building block comprised the EDC-mediated installation of the suitably protected nucleobase followed by saponification using 4 M lithium hydroxide in methanol Scheme 3. Nucleobases thymine and cytosine were incorporated via methylene bridges.
Since thymine does not contain any side chain which is to be protected so thymine acetic acid was used as such but the exocyclic amino group of cytosine was protected to prevent self-condensation. The amino group of nucleobase cytosine was protected using the benzyloxycarbonyl Cbz group and then introduction of acetic acid was carried out for coupling on backbone Scheme 2.
Synthesis of thiol-modified PNA monomer containing pyrimidine nucleobases. Email this article Login required. Email the author Login required. Save to Mendeley. Save to Zotero. Current Issue. Abstract The reaction of methyldopa with o-vanillin in refluxing ethanol afforded Schiff base and characterized through physical analysis with a number of spectra also the study of biological activity.
The geometry of the Schiff base was identified through using C. The prepared complexes were characterized by using Mass, FT-IR and UV-Vis spectral studies, on other than magnetic properties and flame atomic absorption, conductivity measurements. Fetching data from CrossRef. This may take some time to load. Loading related content. Jump to main content. Jump to site search. You do not have JavaScript enabled.
Please enable JavaScript to access the full features of the site or access our non-JavaScript page. Issue 4, From the journal: CrystEngComm. You have access to this article. Please wait while we load your content Something went wrong. Try again? Cited by.
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