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N-Hydroxysuccinimide Esters in Peptide Synthesis

Polymeric N-hydroxysuccinimide esters in the synthesis of N-4 ..

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The Use of Esters of N-Hydroxysuccinimide in Peptide Synthesis

Herein, a simple two-step process for the synthesis and subsequent separation of the two isomers of the N-hydroxysuccinimide esters of 5 and 6-carboxyfluorescein diacetate and 5 and 6-carboxytetraethylrhodamine is reported. The proposed routes have multiple advantages over existing methods in terms of scale, speed and ease of separation of the two isomers.

Synthesis of N-hydroxysuccinimide esters using polymer bound ..

N2 - The design, synthesis, characterization, and preliminary biological assessment of three dendrimers are reported. All three dendrimers, 1-3, present twelve paclitaxel groups linked by acylation of the 2′-hydroxyl group. The linker for dendrimers 2 and 3 also includes a disulfide. Installation of the paclitaxel group relies on reacting twelve primary amines of a second generation triazine dendrimer, a scaffold available on kilogram scale, with a dichlorotriazine bearing the drug. This dichlorotriazine is available in four steps by (i) reacting paclitaxel with glutaric anhydride, (ii) activating with N-hydroxysuccinimide (NHS), (iii) treating the resulting ester with either 1,3-diaminopropane (for 1) or cystamine (for 2 and 3), and (iv), finally, reacting with cyanuric chloride. After reaction with the dendrimer, the resulting monochlorotriazine groups are reacted with 4-aminomethylpiperidine (AMP) and then a poly(ethylene glycol) (PEG) group of molecular weight 2 kDa. Two different PEG-NHS esters are employed that differ in lability. For 1 and 2, the PEG incorporates an ester-linked succinic acid group. For 3, the PEG incorporates an ether-linked acetic acid group. Both mass spectrometry and 1H NMR spectroscopy prove valuable for determining the final ratios of dendrimer:paclitaxel:AMP:PEG. These values are typically 1:12:12:9. Cytotoxicity of these constructs using an MTT-based assay and PC-3 cells reveals IC50 values in the low nanomolar range with dithiothreitol and glutathione enhancing the toxicity of the disulfide-containing constructs 2 and 3. Preliminary toxicology assessment of 1 suggests that it is well tolerated in vivo with preferential renal clearance. The elimination half-lives of all of the dendrimers appear shorter than predicted from the previous results. Tumor localization is observed for all the three dendrimers.

Biotin N Hydroxysuccinimide Ester Synthesis

Use of esters of N-hydroxysuccinimide in the synthesis …

Diacetate protection of 5 and 6-carboxyfluorescein followed by synthesis of the N-hydroxysuccinimide esters allowed ready separation of the two isomers on a multi-gram scale. The 5 and 6-carboxyrhodamine B N-hydroxysuccinimide esters were also readily synthesised and separated.

The separation of the 5 and 6-isomers of carboxyfluorescein by chromatography or crystallisation has been reported but the latter method, in our hands, was inconsistent and not easily reproduced. A recent review supports the view that a more efficient method of separation of the isomers is necessary. Another fluorophore that is also used as a mixture is (5)6-carboxyrhodamine B. Rhodamine dyes are highly fluorescent and have good photostability, and therefore have broad applications, such as a fluorescence standard for quantum yield determinations, detection of reactive oxygen species, ion sensors in living cells, DNA and protein labelling to name but a few. The efficient synthesis of 5 or 6-carboxytetraethylrhodamine N-hydroxysuccinimide ester is not well established.

Convenient Synthesis of N-Hydroxysuccinimide Esters …

Synthesis of squaraine-N-hydroxysuccinimide esters …

Fung reported the synthesis of 5 and 6-carboxytetraethylrhodamine N-hydroxysuccinimide esters using N,N-disuccinimidyl carbonate (DSC) and DMAP, but in our hands, this gave a mixture of starting material and the di-ester product ().

Synthesis began with acetylation of the phenol moieties of fluorescein, modifying the procedure reported by Tour using acetic anhydride and pyridine (>15 g scale, >95% yield), with a mild acid wash being the only work-up necessary (). Carboxylic acid activation used N,N′-diisopropylcarbodiimide (DIC) and N-hydroxysuccinimide (NHS) in dichloromethane. The two carboxyfluorescein diacetate N-hydroxysuccinimide esters were readily purified on a plug of silica gel (7 × 15 cm) using an optimised solvent system of EtOAc/Toluene (20:80) to give a 35% yield of 5-isomer and 25% yield of 6-isomer.

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The latter was converted to the methyl ester.

The design, synthesis, characterization, and preliminary biological assessment of three dendrimers are reported. All three dendrimers, 1-3, present twelve paclitaxel groups linked by acylation of the 2′-hydroxyl group. The linker for dendrimers 2 and 3 also includes a disulfide. Installation of the paclitaxel group relies on reacting twelve primary amines of a second generation triazine dendrimer, a scaffold available on kilogram scale, with a dichlorotriazine bearing the drug. This dichlorotriazine is available in four steps by (i) reacting paclitaxel with glutaric anhydride, (ii) activating with N-hydroxysuccinimide (NHS), (iii) treating the resulting ester with either 1,3-diaminopropane (for 1) or cystamine (for 2 and 3), and (iv), finally, reacting with cyanuric chloride. After reaction with the dendrimer, the resulting monochlorotriazine groups are reacted with 4-aminomethylpiperidine (AMP) and then a poly(ethylene glycol) (PEG) group of molecular weight 2 kDa. Two different PEG-NHS esters are employed that differ in lability. For 1 and 2, the PEG incorporates an ester-linked succinic acid group. For 3, the PEG incorporates an ether-linked acetic acid group. Both mass spectrometry and 1H NMR spectroscopy prove valuable for determining the final ratios of dendrimer:paclitaxel:AMP:PEG. These values are typically 1:12:12:9. Cytotoxicity of these constructs using an MTT-based assay and PC-3 cells reveals IC50 values in the low nanomolar range with dithiothreitol and glutathione enhancing the toxicity of the disulfide-containing constructs 2 and 3. Preliminary toxicology assessment of 1 suggests that it is well tolerated in vivo with preferential renal clearance. The elimination half-lives of all of the dendrimers appear shorter than predicted from the previous results. Tumor localization is observed for all the three dendrimers.

17/03/2016 · N-Hydroxysuccinimide ..

AB - The design, synthesis, characterization, and preliminary biological assessment of three dendrimers are reported. All three dendrimers, 1-3, present twelve paclitaxel groups linked by acylation of the 2′-hydroxyl group. The linker for dendrimers 2 and 3 also includes a disulfide. Installation of the paclitaxel group relies on reacting twelve primary amines of a second generation triazine dendrimer, a scaffold available on kilogram scale, with a dichlorotriazine bearing the drug. This dichlorotriazine is available in four steps by (i) reacting paclitaxel with glutaric anhydride, (ii) activating with N-hydroxysuccinimide (NHS), (iii) treating the resulting ester with either 1,3-diaminopropane (for 1) or cystamine (for 2 and 3), and (iv), finally, reacting with cyanuric chloride. After reaction with the dendrimer, the resulting monochlorotriazine groups are reacted with 4-aminomethylpiperidine (AMP) and then a poly(ethylene glycol) (PEG) group of molecular weight 2 kDa. Two different PEG-NHS esters are employed that differ in lability. For 1 and 2, the PEG incorporates an ester-linked succinic acid group. For 3, the PEG incorporates an ether-linked acetic acid group. Both mass spectrometry and 1H NMR spectroscopy prove valuable for determining the final ratios of dendrimer:paclitaxel:AMP:PEG. These values are typically 1:12:12:9. Cytotoxicity of these constructs using an MTT-based assay and PC-3 cells reveals IC50 values in the low nanomolar range with dithiothreitol and glutathione enhancing the toxicity of the disulfide-containing constructs 2 and 3. Preliminary toxicology assessment of 1 suggests that it is well tolerated in vivo with preferential renal clearance. The elimination half-lives of all of the dendrimers appear shorter than predicted from the previous results. Tumor localization is observed for all the three dendrimers.

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