Activated esters

Primary or secondary amino groups are ubiquitous in biomolecules. They are present in proteins and peptides as ε-amino groups of lysines and N-terminal amino groups. Many natural and synthetic small molecules are amines, and DNAs with amino groups can be prepared by solid phase synthesis, and enzymatically.

Amino groups can be modified by acylation with various activated carbonyl compounds. Among these compounds, activated N-hydroxysuccinimide esters are most suitable for biolabeling and bioconjugation applications.

NHS ester coupling chemistry

Compared to other activated esters, NHS derivatives possess good stability in aqueous environment. Optimal pH for the coupling of amines with NHS esters in aqueous buffers is 8.3-8.5. Labeling is also possible in organic solvents. Polar aprotic solents, such as DMF or DMSO, are preferred. One equivalent of tertiary amine base, such as triethylamine, or diisopropylethylamine (DIPEA) is necessary to achieve efficient amine acylation in non-aqueous solution.

(5,6)-FAM diacetate NHS ester

Amine-reactive fluorescein (FAM) derivative, a mixture of 5- and 6-isomers. The reagent becomes brightly green fluorescent once it is hydrolyzed while diffusing into cells. A fluorescent tracer.
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Cat. # Quantity Price Lead time
2934-1mg 1 mg –   in stock
2934-25mg 25 mg $160 in stock
2934-50mg 50 mg $270 in stock
2934-100mg 100 mg $520 in stock
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AF 343 (Coumarin)-X-NHS ester

AF 343 (Coumarin) is a blue emitting dye that can serve as a FRET donor for fluorescein (FAM). This structure features a linker between Coumarin 343 fluorophore, and the functional group. It provides better solubility, and spatial separation between the dye, and the functional group.
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Cat. # Quantity Price Lead time
12620 1 mg $110 in stock
22620 5 mg $210 in stock
42620 25 mg $410 in stock
52620 50 mg $695 in stock
62620 100 mg $1190 in stock
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AF 430 NHS ester

AF 430 is a hydrophilic coumarin dye with emission in the green-yellow range. The NHS ester is used for the labeling of amine groups.
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Cat. # Quantity Price Lead time
10820 1 mg $110 in stock
20820 5 mg $165 in stock
40820 25 mg $380 in stock
50820 50 mg $695 in stock
60820 100 mg $1190 in stock
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AF 488 NHS ester

AF 488 NHS ester, a bright, photostable, and hydrophilic fluorescent dye for the green channel.
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Cat. # Quantity Price Lead time
11820 1 mg $125 in stock
21820 5 mg $325 in stock
31820 10 mg $480 in stock
41820 25 mg $950 in stock
51820 50 mg $1625 in stock
61820 100 mg $2090 in stock
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AF 488 TFP ester

Tetrafluorophenyl ester of green fluorescent dye AF 488 for labeling amino groups in proteins, peptides, and modified oligonucleotides.
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Cat. # Quantity Price Lead time
118T0 1 mg $165 in stock
218T0 5 mg $510 in stock
418T0 25 mg $1650 in stock
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AF 532 NHS ester

NHS-ester of AF 532 dye for protein, peptide, and modified oligonucleotide labeling via reaction with amino groups.
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Cat. # Quantity Price Lead time
1C820 1 mg $140 in stock
2C820 5 mg $450 in stock
4C820 25 mg $1460 in stock
5C820 50 mg $1890 in stock
6C820 100 mg $2640 5 days
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AF 555 NHS ester

AF 555 NHS ester, a bright, photostable, and hydrophilic fluorescent dye for the yellow channel.
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Cat. # Quantity Price Lead time
1K820 1 mg $140 in stock
2K820 5 mg $450 in stock
4K820 25 mg $1460 in stock
5K820 50 mg $1890 in stock
6K820 100 mg $2640 in stock
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AF 568 NHS ester

AF 568 derivative for labeling proteins and other high- and low-molecular weight ligands with free amines.
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Cat. # Quantity Price Lead time
14820 1 mg $125 in stock
24820 5 mg $325 in stock
44820 25 mg $720 in stock
54820 50 mg $1325 in stock
64820 100 mg $2090 in stock
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AF 594 NHS ester

Red-fluorescent NHS-ester of AF 594 dye for labeling proteins, peptides, antibodies, and any molecules containing an -NH2 group. Pure 5-isomer
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Cat. # Quantity Price Lead time
2825-1mg 1 mg $125 5 days
2825-5mg 5 mg $425 5 days
2825-25mg 25 mg $1240 in stock
2825-50mg 50 mg $1890 in stock
2825-100mg 100 mg $2640 5 days
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AF 647 NHS ester

Bright, water-soluble succinimide ester of AF 647 dye for protein and antibody labeling.
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Cat. # Quantity Price Lead time
16820 1 mg $140 in stock
26820 5 mg $450 in stock
46820 25 mg $1460 in stock
56820 50 mg $1890 in stock
66820 100 mg $2640 in stock
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AMCA NHS ester

NHS-ester of AMCA dye for protein, peptide, and modified oligonucleotide labeling via reaction with amino groups. AMCA is one of the brightest blue fluorescent dyes with large Stoke's shift and high resistance to photobleaching.
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Cat. # Quantity Price Lead time
3606-5mg 5 mg $110 in stock
3606-25mg 25 mg $290 in stock
3606-50mg 50 mg $435 in stock
3606-100mg 100 mg $595 in stock
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BDP 558/568 NHS ester

BDP 558/568 is a fluorophore for the yellow region of the spectrum. Like other BDP dyes, this fluorophore has high fluorescence quantum yield, brightness, and photostability.
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Cat. # Quantity Price Lead time
17420 1 mg $125 in stock
27420 5 mg $260 in stock
47420 25 mg $510 in stock
57420 50 mg $895 in stock
67420 100 mg $1490 in stock
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BDP 564/570 NHS ester

Lypohilic borodipyrromethene dye with orange emission for the labeling of primary and secondary amine groups.
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Cat. # Quantity Price Lead time
1H420 1 mg $125 in stock
2H420 5 mg $325 in stock
4H420 25 mg $510 in stock
5H420 50 mg $895 in stock
6H420 100 mg $1490 in stock
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BDP 576/589 NHS ester

BDP 576/589 NHS ester is a bright hydrophobic dye with emission in the orange spectrum range. It can be used in fluorescence anisotropy assays.
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Cat. # Quantity Price Lead time
1G420 1 mg $125 in stock
2G420 5 mg $260 in stock
4G420 25 mg $510 in stock
5G420 50 mg $895 in stock
6G420 100 mg $1490 in stock
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BDP 581/591 NHS ester

NHS ester derivative of BDP 581/591 borondipyrromethene fluorophore for the labeling of proteins, peptides, and other biomolecules. The dye is useful for fluorescence polarization and two-photon experiments, and as a ROS probe.
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Cat. # Quantity Price Lead time
16420 1 mg $125 in stock
26420 5 mg $260 in stock
46420 25 mg $510 in stock
56420 50 mg $895 in stock
66420 100 mg $1490 in stock
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BDP 630/650-X-NHS ester

BDP 630/650 is a borondipyrromethene fluorophore tuned to Cyanine5 excitation and emission channels. The dye is bright and highly photostable. It is useful for fluorescence polarization assays. This is an amine-reactive NHS ester derivative.
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Cat. # Quantity Price Lead time
15420 1 mg $125 in stock
25420 5 mg $260 in stock
45420 25 mg $510 in stock
55420 50 mg $895 in stock
65420 100 mg $1490 in stock
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BDP 650/665-X-NHS ester

Amine reactive of BDP 650/665, a borondipyrromethene dye for Cy5 channel, possessing a high molar extinction coefficient, and a good emission quantum yield.
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Cat. # Quantity Price Lead time
1E420 1 mg $125 in stock
2E420 5 mg $260 in stock
4E420 25 mg $510 in stock
5E420 50 mg $895 in stock
6E420 100 mg $1490 in stock