Shop All Aldehyde-, Ketone-, & Carboxylate-Reactive Labels

EZ-Link™ Amine-PEG11-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Amine-PEG11-Biotin is a biotinylation reagent containing a long 11-unit polyethylene glycol (PEG) spacer arm and a terminal primary amine group for conjugation and protein labeling with EDC or other crosslinkers.

Features of EZ-Link Amine-PEG11-Biotin:

Biotinylation—label molecules and surfaces for assays or affinity purification methods involving avidin or streptavidin probes and resins
Amine-activated—primary amine can be crosslinked to proteins and material surfaces using EDC and other crosslinkers
Pegylated—the 11-unit, polyethylene glycol (PEG) group in spacer arm enhances water solubility of biotinylated molecules
Long reach—total reagent length is more than 50 angstroms, greatly minimizing steric hindrance for the biotin binding-function

Amine-PEG11-Biotin is the longest of three amine-modified biotin compounds that contain polyethylene glycol (PEG) spacer arms. The 11-unit PEG segment is hydrophilic and confers greater solubility to labeled proteins compared to reagents having only hydrocarbon spacers. The primary amine of this pegylated biotin reagent can be conjugated to carboxyl groups on carboxy termini, aspartate residues or glutamate residues using EDC (Part No. 22980), a water-soluble carbodiimide crosslinker. EDC activates carboxyl groups to bind to the—NH2 group of the amino-biotin, forming an amide bond.

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Amino-biotin compounds can be conjugated to functional groups of proteins and other molecules in a variety of ways. The most common method is to crosslink the terminal primary amine to carboxyl groups using . Carboxyl groups (-COOH) occur in aspartate or glutamate residues and the carboxy-terminus of polypeptides. When activated with EDC (Part No. 22980), carboxylates react with amino (—NH2) groups to form amide bonds. Carboxylate molecules and surface materials can be pre-activated using EDC with Sulfo-NHS (Part No. 24510) for subsequent reaction to primary amines (see NHS-ester Chemistry).

Alexa Fluor™ 568 Hydrazide, for microinjection (Invitrogen™)

Alexa Fluor® 568 Hydrazide is useful as a cell tracer and as a reactive dye for labeling aldehydes or ketones in polysaccharides or glycoproteins. This version is formatted as a ready-to-use solution that is dissolved in a 200 mM KCl solution and filter sterilized.

Alexa Fluor® 568 is a bright, red fluorescent dye. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 568 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 568 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

Detailed information about this AlexaFluor® hydrazide:

• Fluorophore label : Alexa Fluor® 568 dye
• Reactive group: hydrazide
• Reactivity: Aldehydes or keytones in polysaccharides or glycoproteins
• Ex/Em of the conjugate: 576/599 nm
• Extinction coefficient: 86,000 cm-1M-1
• Spectrally similar dyes: Rhodamine Red
• Molecular weight: 730.74

Cell Tracking and Tracing Applications
Alexa Fluor® hydrazides and hydroxlamines are useful as low molecular weight, membrane-impermeant, aldehyde-fixable cell tracers, exhibiting brighter fluorescence and greater photostability than cell tracers derived from other spectrally similar fluorophores. They are easily loaded into cells by microinjection, infusion from patch pipette, or uptake induced by our Influx™ Pinocytic Cell-Loading Reagent. It is designed to be loaded into cells by microinjection or infusion from patch pipette. Learn more about cell tracking and tracing.

Glycoprotein and Polysaccharide Labeling Applications
The Alexa Fluor® hydrazides and hydroxlamines are reactive molecules that can be used to add a fluorescent label to biomolecules containing aldehydes or ketones. Aldehydes and ketones can be introduced into polysaccharides and glycoproteins by periodate-mediated oxidation of vicinal diols. Galactose oxidase can also be used to oxidize terminal galactose residues of glycoproteins to aldehydes.

Hydrazide vs Hydroxylamine
Hydrazine derivatives react with ketones and aldehydes to yield relatively stable hydrazones. Hydroxylamine derivatives (aminooxy compounds) react with aldehydes and ketones to yield oximes. Oximes are superior to hydrazones with respect to hydrolytic stability. Both hydrazones and oximes can be reduced with sodium borohydride (NaBH4) to further increase the stability of the linkage.

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits to fit your starting material and your experimental setup. See our Antibody Labeling kits or use our Labeling Chemistry Selection Tool for other choices. To learn more about our labeling kits, read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in The Molecular Probes® Handbook.

We’ll Make a Custom Conjugate for You
If you can’t find what you’re looking for in our online catalog, we’ll prepare a custom antibody or protein conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

Related Products
DMSO (dimethylsulfoxide) (D12345)
Antibody Conjugate Purification Kit for 0.5-1 mg (A33086)
Antibody Conjugate Purification Kit for 20-50 µg (A33087)
Antibody Conjugate Purification kit for 50-100 µg (A33088)

EZ-Link™ Alkoxyamine-PEG4-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Alkoxyamine-PEG4-Biotin is a biotinylation reagent containing a four-unit polyethylene glycol (PEG) spacer for biotinylating macromolecules at carbohydrate groups that have been oxidized to form aldehydes.

Features of EZ-Link Alkoxyamine-PEG4-Biotin:

Glycoprotein labeling—biotinylate glycosylated proteins at sialic acid residues for detection or purification using streptavidin probes or resins
Cell surface labeling—biotinylate and isolate cell surface glycoproteins; reagent does not permeate membranes of whole cells
Aldehyde-reactive—reacts with aldehydes formed by periodate-oxidation of sugar groups
Alkoxyamine-activated—aminooxy group forms more stable linkages than hydrazide reagents
Pegylated – spacer arm contains a hydrophilic, 4-unit, polyethylene glycol (PEG) group
Enhances solubility – pegylation imparts water solubility to the biotinylated molecule, helping to prevent aggregation of biotinylated antibodies stored in solution
Irreversible—forms stable (permanent) oxime bonds; spacer arm cannot be cleaved
Solubility—usually dissolved in DMSO to make concentrated stock solution
Medium length—spacer arm (total length added to target) is 27.0 angstroms, sufficient to minimize steric hindrance for binding

Aminooxy-biotin reagents such as this one are useful for biotinylating glycoproteins and other molecules that have oxidizable polysaccharides groups. The alkoxyamine group (also called an aminooxy or aminoxy group) conjugates to aldehydes of oxidized sugars. EZ-Link Alkoxyamine-PEG-Biotin reagents contain a multi-functional extended spacer arm that is a flexible, non-immunogenic hydrophilic polyethylene glycol (PEG), which imparts water solubility to labeled molecules. Consequently, antibodies labeled with pegylated biotin reagents exhibit less aggregation when stored in solution compared to antibodies labeled with reagents having only hydrocarbon spacers.

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Biotinylation reagents differ in reactivity, length, solubility, cell permeability and cleavability. Hydrazides and alkoxyamines are two types of carbonyl-reactive groups. Alkoxyamines (—O-NH2) react specifically with aldehyde groups in near-neutral conditions to form stable oxime linkages. The reaction is more efficient in the presence of aniline (Part No. 88944). Alternatively, alkoxyamines can be conjugated to carboxylic acids using EDC carbodiimide chemistry.

Reactive aldehyde groups can be generated in glycoproteins and other polysaccharide compounds by oxidation of constituent sugar diols using sodium periodiate (Part No. 20504). Sialic acid residues are common components of protein glycosylation and are easily converted to aldehydes with 1 mM NaIO4.

Alexa Fluor™ 594 Hydrazide, for microinjection (Invitrogen™)

Alexa Fluor® 594 Hydrazide is useful as a cell tracer and as a reactive dye for labeling aldehydes or ketones in polysaccharides or glycoproteins. This version is formatted as a ready-to-use solution that is dissolved in a 200 mM KCl solution and filter sterilized.

Alexa Fluor® 594 is a bright, red fluorescent dye. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 594 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 594 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

Detailed information about this AlexaFluor® hydrazide:

• Fluorophore label : Alexa Fluor® 594 dye
• Reactive group: hydrazide
• Reactivity: Aldehydes or keytones in polysaccharides or glycoproteins
• Ex/Em of the conjugate: 588/613 nm
• Extinction coefficient: 97,000 cm-1M-1
• Spectrally similar dyes: Texas Red
• Molecular weight: 758.79

Cell Tracking and Tracing Applications
Alexa Fluor® hydrazides and hydroxlamines are useful as low molecular weight, membrane-impermeant, aldehyde-fixable cell tracers, exhibiting brighter fluorescence and greater photostability than cell tracers derived from other spectrally similar fluorophores. They are easily loaded into cells by microinjection, infusion from patch pipette, or uptake induced by our Influx™ Pinocytic Cell-Loading Reagent. Learn more about cell tracking and tracing.

Glycoprotein and Polysaccharide Labeling Applications
The Alexa Fluor® hydrazides and hydroxlamines are reactive molecules that can be used to add a fluorescent label to biomolecules containing aldehydes or ketones. Aldehydes and ketones can be introduced into polysaccharides and glycoproteins by periodate-mediated oxidation of vicinal diols. Galactose oxidase can also be used to oxidize terminal galactose residues of glycoproteins to aldehydes.

Hydrazide vs Hydroxylamine
Hydrazine derivatives react with ketones and aldehydes to yield relatively stable hydrazones. Hydroxylamine derivatives (aminooxy compounds) react with aldehydes and ketones to yield oximes. Oximes are superior to hydrazones with respect to hydrolytic stability. Both hydrazones and oximes can be reduced with sodium borohydride (NaBH4) to further increase the stability of the linkage.

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits to fit your starting material and your experimental setup. See our Antibody Labeling kits or use our Labeling Chemistry Selection Tool for other choices. To learn more about our labeling kits, read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in The Molecular Probes® Handbook.

We’ll Make a Custom Conjugate for You
If you can’t find what you’re looking for in our online catalog, we’ll prepare a custom antibody or protein conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

Related Products
DMSO (dimethylsulfoxide) (D12345)
Antibody Conjugate Purification Kit for 0.5-1 mg (A33086)
Antibody Conjugate Purification Kit for 20-50 µg (A33087)
Antibody Conjugate Purification kit for 50-100 µg (A33088)

BODIPY™ TR Cadaverine (5-(((4-(4,4-Difluoro-5-(2-Thienyl)-4-Bora-3a,4a-Diaza-s-Indacene-3-yl)phenoxy)acetyl)amino)pentylamine, Hydrochloride) (Invitrogen™)

The amine-containing BODIPY® TR cadaverine can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a generate stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3). Carboxylic acids of proteins and other water-soluble biopolymers can be coupled to this molecule in aqueous solution using water-soluble carbodiimides such as EDAC (E2247). The electronically neutral BODIPY® TR dye is spectrally similar to the red fluorescent Texas Red®® dye.

EZ-Link™ Hydrazide-PEG4-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Hydrazide-PEG4-Biotin (also called Biotin-PEG4-Hydrazide) is an aldehyde-reactive biotinylation reagent that contains a 4-unit polyethylene glycol (PEG) spacer arm for increased hydrophilicity.

Features of EZ-Link Hydrazide-PEG4-Biotin:

Glycoprotein labeling—biotinylate glycosylated proteins at sialic acid residues for detection or purification using streptavidin probes or resins
Cell surface labeling—biotinylate and isolate cell surface glycoproteins; reagent does not permeate membranes of whole cells
Aldehyde-reactive—reacts with aldehydes formed by periodate-oxidation of sugar groups
Hydrazide-activated—perform reactions at pH 4 to 6 in buffers such as sodium acetate
Pegylated – spacer arm contains a hydrophilic, 4-unit, polyethylene glycol (PEG) group
Enhances solubility – pegylation imparts water solubility to the biotinylated molecule, helping to prevent aggregation of biotinylated antibodies stored in solution
Irreversible—forms semi-permanent hydrazone bonds; spacer arm cannot be cleaved
Solubility—usually dissolved in DMSO to make concentrated stock solution
Long reach—spacer arm (total length added to target) is 31.3 angstroms

Biotin-PEG4-Hydrazide enables biotinylation of glycoproteins and other molecules containing aldehydes or oxidizable sugar groups. The hydrazide group reacts spontaneously with aldehyde or ketone groups to form a stable hydrazone bond. Aldehyde groups can be created by gentle periodate oxidation of cis-diols in sialic acid and other sugars in carbohydrates. The hydrophilic, 4-unit polyethylene glycol (PEG) spacer arm imparts water solubility that is transferred to the biotinylated molecule, thus reducing aggregation of labeled proteins stored in solution. The PEG segment also adds length and flexibility to the spacer arm, minimizing steric hindrance involved with binding to avidin molecules.

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Biotinylation reagents differ in reactivity, length, solubility, cell permeability and cleavability. Hydrazides and alkoxyamines are two types of carbonyl-reactive groups. Hydrazides (—NH-NH2) react specifically with aldehyde groups in slightly acidic conditions to form hydrazone linkages; these can be further reduced to stable secondary amine bonds using sodium cyanoborohydride (Part No. 44892). The reaction is more efficient in the presence of aniline (Part No. 88944). Alternatively, hydrazides can be conjugated to carboxylic acids using EDC carbodiimide chemistry.

Reactive aldehyde groups can be generated in glycoproteins and other polysaccharide compounds by oxidation of constituent sugar diols using sodium periodiate (Part No. 20504). Sialic acid residues are common components of protein glycosylation and are easily converted to aldehydes with 1 mM NaIO4.

APTS (8-Aminopyrene-1,3,6-Trisulfonic Acid, Trisodium Salt) (Invitrogen™)

The aromatic amine of APTS (8-aminopyrene-1,3,6-trisulfonic acid, trisodium salt) can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3) to form new biotinylated probes.

Oregon Green™ 488 Cadaverine, 5-isomer (Invitrogen™)

The primary aliphatic amine of the green fluorescent Oregon Green® cadaverine can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3) to form new biotinylated probes. Carboxylic acids of proteins and other water-soluble biopolymers can be coupled to this molecule in aqueous solution using water-soluble carbodiimides such as EDAC (E2247). This molecule can also be used as a water-soluble, fixable polar tracer.

EZ-Link™ Pentylamine-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Pentylamine-Biotin is biotin that has been conjugated to pentylenediamine to add a short, amine-terminated spacer to its valeric acid group, providing a simple amine-modified compound for different applications.

Features of EZ-Link Pentylamine-Biotin:

Biotinylation—label molecules and surfaces for assay or affinity purification methods involving avidin or streptavidin probes and resins
Amine-activated—primary amine can be crosslinked to proteins and material surfaces using EDC and other crosslinkers
Medium length—spacer arm (total length added to target) is 18.9 angstroms, representing a 6-atom extension of the native biotin valeric acid (and its conversion to a primary amine)

Pentylamine Biotin is a compound formed by modification of the valeric acid side chain of biotin with pentane-1,5-diamine. The compound contains terminal primary amine (-NH2), which provides a functional handle for derivatization or conjugation to proteins, surfaces and other molecules. Carbodiimide (EDC) and NHS-ester crosslinker chemistries are most often utilized for covalent modifications involving amino-biotin molecules. The compound is also useful as an amine-alternative to native (carboxylate) biotin for assays and methods that require a biotin standard or blocking step.

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Amino-biotin compounds can be conjugated to functional groups of proteins and other molecules in a variety of ways. The most common method is to crosslink the terminal primary amine to carboxyl groups using . Carboxyl groups (-COOH) occur in aspartate or glutamate residues and the carboxy-terminus of polypeptides. When activated with EDC (Part No. 22980), carboxylates react with amino (—NH2) groups to form amide bonds. Carboxylate molecules and surface materials can be pre-activated using EDC with Sulfo-NHS (Part No. 24510) for subsequent reaction to primary amines (see NHS-ester Chemistry).

Applications:
• Used for colorimetric assays for Factor XIII and cellular transglutaminase

Alexa Fluor™ 405 Cadaverine (Invitrogen™)

Alexa Fluor® 405 Cadaverine is useful as a polar tracer and as a reactive dye for labeling proteins via a carboxylic acid moiety. Alexa Fluor® 405 is a bright, violet dye with excitation ideally suited to the 405 nm laser line. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 405 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 405 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

Detailed information about this AlexaFluor® cadaverine:

• Fluorophore label : Alexa Fluor® 405 dye
• Reactive group: cadaverine
• Reactivity: carboxylic acids, aldehydes, and ketones (and glutamine residues through an enzyme-catalyzed transamidation reaction)
• Ex/Em of the conjugate: 399/422 nm
• Extinction coefficient: 29,000 cm-1M-1
• Spectrally similar dyes: Cascade Blue
• Molecular weight: 666.58

Cell Tracking and Tracing Applications
Alexa Fluor® cadaverines make excellent fluorescent polar tracers because they are bright, small, and water soluble. Since they contain an aldehyde-fixable functional group, they can be fixed in cells by treatment with formaldehyde or glutaraldehyde. They are easily loaded into cells by microinjection, infusion from patch pipette, or uptake induced by our Influx™ Pinocytic Cell-Loading Reagent. Learn more about cell tracking and tracing.

Protein Labeling Applications
Alexa Fluor® cadaverines can be used as reactive molecules for adding a fluorescent label to carboxylic acids using a coupling agent such as a carbodiimide; they do not spontaneously react with carboxylic acids in solution. They do, however, react spontaneously with the common amine-reactive functional groups, including succinimidyl esters and isothiocyanates. The amine-containing Alexa Fluor® cadaverines can also be used to label glutamine residues in some proteins and peptides via an enzyme-catalyzed transamidation reaction.

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits to fit your starting material and your experimental setup. See our Antibody Labeling kits or use our Labeling Chemistry Selection Tool for other choices. To learn more about our labeling kits, read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in The Molecular Probes® Handbook.

We’ll Make a Custom Conjugate for You
If you can’t find what you’re looking for in our online catalog, we’ll prepare a custom antibody or protein conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

Related Products
DMSO (dimethylsulfoxide) (D12345)
Antibody Conjugate Purification Kit for 0.5-1 mg (A33086)
Antibody Conjugate Purification Kit for 20-50 µg (A33087)
Antibody Conjugate Purification kit for 50-100 µg (A33088)

Qdot™ 545 ITK™ Carboxyl Quantum Dots (Invitrogen™)

Qdot® 545 ITK™ carboxyl quantum dots are the ideal starting material for preparing custom conjugates that require high loading of biomolecules. These materials are carboxylate functionalized and can be coupled to amine groups of proteins and modified oligonucleotides using EDC-mediated condensation. The coatings of these probes provides more binding sites than our Qdot® ITK™ amino quantum dots, but lacks PEG linkers that help to prevent non-specific interactions. These materials can be conjugated to X-PEG-amine bi-functional linkers for custom reactivity and higher specificity. Our Qdot® ITK™ carboxyl quantum dots are provided as 8 µM solutions and are available in all 9 Qdot® probe colors.

Important Features of Qdot® ITK™ Carboxyl Quantum Dots:
• Qdot® 545 ITK™ carboxyl quantum dot has emission maxima of ~545 nm
• Extremely photostable and bright fluorescence
• Efficiently excited with single-line excitation sources
• Narrow emission, large Stokes shift
• Available in multiple colors
• Ideal labeling and tracking applications


Properties of Qdot® Nanocrystals
Qdot® probes are ideal for imaging and labeling applications that require bright fluorescent signals and/or real-time tracking. Unique among fluorescent reagents, all nine available colors of Qdot® probes can be simultaneously excited with a single (UV to blue-green) light source. This property makes these reagents excellent for economical and user-friendly multiplexing applications. Qdot® labels are based on semiconductor nanotechnology and are similar in scale to moderately sized proteins.

About the Innovator’s Tool Kit Qdot® ITK™ Reagents
These Qdot® ITK™ probes are ideal for researchers who wish to prepare specific (non-stocked) conjugates for their applications and need customizable conjugation functionality.

Other Forms of Qdot® Nanocrystals are Available
In addition to the carboxyl-derivatized form, we offer Qdot® ITK™ quantum dots with amino and aliphatic hydrocarbon modifications. We’ve also developed a wide range of Qdot® nanocrystals conjugates and labeling kits. Investigate the properties of Qdot® nanocrystals or read the Molecular Probes® Handbook Section 6.6—Qdot® Nanocrystals to find out more.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Tetramethylrhodamine Cadaverine, 5-(and-6)-((N-(5-Aminopentyl) Amino) Carbonyl) Tetramethylrhodamine, mixed isomers (Invitrogen™)

The primary aliphatic amine of tetramethylrhodamine cadaverine can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a generate stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3). Carboxylic acids of proteins and other water-soluble biopolymers can be coupled to this molecule in aqueous solution using water-soluble carbodiimides such as EDAC (E2247). This material consists of the 5- and 6- isomer. Please see the structure for additional details.

EZ-Link™ Amine-PEG2-Biotin (Thermo Scientific™)

Thermo Scientific EZ-Link Amine-PEG2-Biotin is a water-soluble biotin compounds containing a polyethylene glycol (PEG) spacer arm and a terminal primary amine for conjugation via EDC and other crosslinker methods.

Features of EZ-Link Amine-PEG2-Biotin:

Biotinylation—label molecules and surfaces for assays or affinity purification methods involving avidin or streptavidin probes and resins
Amine-activated—primary amine can be crosslinked to proteins and material surfaces using EDC and other crosslinkers
Pegylated—polyethylene glycol (PEG) groups in spacer arm enhances water solubility of biotinylated molecules
Medium length—spacer arm (total length added to target) is 20.4 angstroms

Amine-PEG2-Biotin and Amine-PEG3-Biotin are the shorter two of three amine-modified biotin compounds that contain polyethylene glycol (PEG) spacer arms. The short PEG segments are hydrophilic and confer greater solubility to labeled proteins compared to reagents having only hydrocarbon spacers. The primary amines of these pegylated biotin reagents can be conjugated to carboxyl groups on carboxy termini, aspartate residues or glutamate residues using EDC (Part No. 22980), a water-soluble carbodiimide crosslinker. EDC activates carboxyl groups to bind to the—NH2 group of the amino-biotin, forming an amide bond.

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Amino-biotin compounds can be conjugated to functional groups of proteins and other molecules in a variety of ways. The most common method is to crosslink the terminal primary amine to carboxyl groups using . Carboxyl groups (-COOH) occur in aspartate or glutamate residues and the carboxy-terminus of polypeptides. When activated with EDC (Part No. 22980), carboxylates react with amino (—NH2) groups to form amide bonds. Carboxylate molecules and surface materials can be pre-activated using EDC with Sulfo-NHS (Part No. 24510) for subsequent reaction to primary amines (see NHS-ester Chemistry).

Related Products
EZ-Link™ Amine-PEG3-Biotin

Alexa Fluor™ 488 Cadaverine (Invitrogen™)

Alexa Fluor® 488 Cadaverine is useful as a polar tracer and as a reactive dye for labeling proteins via a carboxylic acid moiety. Alexa Fluor® 488 is a bright, green-fluorescent dye with excitation ideally suited to the 488 nm laser line. Used for stable signal generation in imaging and flow cytometry, Alexa Fluor® 488 dye is water soluble and pH-insensitive from pH 4 to pH 10. In addition to reactive dye formulations, we offer Alexa Fluor® 488 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection (learn more).

Detailed information about this AlexaFluor® cadaverine:

• Fluorophore label : Alexa Fluor® 488 dye
• Reactive group: cadaverine
• Reactivity: carboxylic acids, aldehydes, and ketones (and glutamine residues through an enzyme-catalyzed transamidation reaction)
• Ex/Em of the conjugate: 493/516 nm
• Extinction coefficient: 73,000 cm-1M-1
• Spectrally similar dyes: FITC, GFP
• Molecular weight: 640.61

Cell Tracking and Tracing Applications
Alexa Fluor® cadaverines make excellent fluorescent polar tracers because they are bright, small, and water soluble. Since they contain an aldehyde-fixable functional group, they can be fixed in cells by treatment with formaldehyde or glutaraldehyde. They are easily loaded into cells by microinjection, infusion from patch pipette, or uptake induced by our Influx™ Pinocytic Cell-Loading Reagent. Learn more about cell tracking and tracing.

Protein Labeling Applications
Alexa Fluor® cadaverines can be used as reactive molecules for adding a fluorescent label to carboxylic acids using a coupling agent such as a carbodiimide; they do not spontaneously react with carboxylic acids in solution. They do, however, react spontaneously with the common amine-reactive functional groups, including succinimidyl esters and isothiocyanates. The amine-containing Alexa Fluor® cadaverines can also be used to label glutamine residues in some proteins and peptides via an enzyme-catalyzed transamidation reaction.

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits to fit your starting material and your experimental setup. See our Antibody Labeling kits or use our Labeling Chemistry Selection Tool for other choices. To learn more about our labeling kits, read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in The Molecular Probes® Handbook.

We’ll Make a Custom Conjugate for You
If you can’t find what you’re looking for in our online catalog, we’ll prepare a custom antibody or protein conjugate for you. Our custom conjugation service is efficient and confidential, and we stand by the quality of our work. We are ISO 9001:2000 certified.

Related Products
DMSO (dimethylsulfoxide) (D12345)
Antibody Conjugate Purification Kit for 0.5-1 mg (A33086)
Antibody Conjugate Purification Kit for 20-50 µg (A33087)
Antibody Conjugate Purification kit for 50-100 µg (A33088)

BODIPY™ FL EDA, 4,4-Difluoro-5,7-Dimethyl-4-Bora-3a,4a-Diaza-s-Indacene-3-Propionyl Ethylenediamine, Hydrochloride (Invitrogen™)

BODIPY® FL EDA can be reversibly coupled to aldehydes and ketones to form a Schiff base - which can be reduced to a generate stable amine derivative by sodium borohydride (NaBH4) or sodium cyanoborohydride (NaCNH3). Carboxylic acids of proteins and other water-soluble biopolymers can be coupled to this molecule in aqueous solution using water-soluble carbodiimides such as EDAC (E2247).