Other Protein Modifiers

Protein Modification Reagents
  • 2-Iminothiolane

    2-Iminothiolane hydrochloride (Traut's Reagent) is a useful reagent for converting primary amine functional groups into free sulfhydryl groups. Traut's reagent (2-IT) is a simple water soluble, ringed molecule that completes this primary amine (-NH2) to sulfhydryl (-SH) conversion reaction in a one-step procedure in the pH range of 7 to 10. Once modification of a protein molecule with 2-Iminothiolane is complete, free amine groups will have been irreversibly converted to a sulfhydryl group with a four atom chain and without significant disruption of the original amine groups protonation state.

    After incorporation of the Traut's free sulfhydryl into a protein or otherwise, this -SH group makes for a very useful handle for further modification, such as selectively reacting this modified protein with a SMCC or BMPS containing conjugates, creating a permanent bond between two proteins. A 2-Iminothiolane modified protein or peptide could also be used to create a reversible link with an SPDP containing conjugate. Please feel free to contact our technical support staff for further questions specifically related to your application.

    Package Sizes: 500 mg and 1 gram

    Product Numbers: 14104-500mg and 14104-1g

    Product Name: 2-Iminothiolane

    Alternative Names: 2-IT; Traut's Reagent; 4781-83-3; 2-Iminothiolane HCl; 2-Iminothiolane hydrochloride; Dihydro-2-(3H)-thiophenimine hydrochloride; Dihydro-2-(3H)-thiophenimine HCl; C4H8ClNS


    Appearance: White Solid

    Purity: is ≥ 90% by quantitative NMR

    Storage: 4 °C, protected from moisture


    Properties Physical State: Solid

    CAS#: 4781-83-3

    Chemical Formula: C4H8ClNS

    Molecular Weight: 137.63

    Spacer length: 8.1 Å

    Melting Point: 198-201 °C (Lit)

    Tariff Code: 2934.99.9000

  • Citraconic Anhydride

    Citraconic Anhydride is a convenient, reversible amine blocking reagent. This protein modification reagent converts primary amines to amide groups with a terminal carboxylic acid moiety. Citraconic Anhydride reacts with primary amines, such as those found in lysine residues, at pH 7-9. This modification is conveniently reversed at pH 3, rendering a citraconic acid by-product. and returning the amine to its original composition. Alternatively, this reversal can be facilitated in the presence of Hydroxylamine (CovaChem 11304-25).

    Package Sizes: 25 grams and 100 grams

    Product Numbers: 14105-25 and 14105-100

    Product Name: Citraconic Anhydride

    Alternative Names: Citraconic anhydride; 2-Methylmaleic anhydride; CAS No. 616-02-4; C5H4O3


    Appearance: Clear Liquid

    Purity: is ≥ 98% by GC

    Storage: 20-25 °C, protected from moisture

    Properties Physical State: Liquid

    CAS#: 616-02-4

    Chemical Formula: C5H4O3

    Molecular Weight: 112.08

    Boiling Point: 213-214 °C (Lit)

    Melting Point: 6-10 °C (Lit)

    Density: 1.245 g/mL at 25 °C (Lit)

    Refractive Index: 1.47 - 1.472 at 20 °C (Lit)

    Tariff Code: 2917.19.7050

    IATA Code: 2810

    *Important Note: 100 gram size may ship as 4x25 grams to reduce shipping costs.

  • Hydroxylamine Hydrochloride

    Hydroxylamine hydrochloride is a reducing agent that is soluble in aqueous buffers. Hydroxylamine HCl is a reagent used in many biomolecular applications, including the cleavage of Glycine- Asparagine (Gly-Asn) in proteins and peptides.

    This chemical reagent is also recommended for the removal of the acetyl protecting group from N-succinimidyl S-acetylthioacetate (SATA, CovaChem 14102) modified proteins. CovaChem also carries protein crosslinkers, whose spacer arm can be cleaved by Hydroxylamine HCl, including EGS and Sulfo-EGS.

    Package Sizes: 25 grams

    Product Numbers: 13304-25

    Product Name: Hydroxylamine Hydrochloride

    Alternative Names: Hydroxylamine HCl; Hydroxylammonium chloride; 5470-11-1; NH2OH-HCl;


    Appearance: White Crystalline Solid

    Purity: is ≥ 99%

    Storage: Room Temperature, protected from moisture


    Properties Physical State: Solid

    CAS#: 5470-11-1

    Chemical Formula: NH4OCl

    Molecular Weight: 69.49

    International Shipping

    Tariff Code: 2825.10.0000

    IATA (UN Code): 2923

  • Iodoacetamide (IAA)

    CovaChem's Iodoacetamide is a useful reagent for blocking sulfhydryl (cysteine) groups in order to prevent disulfide formation (oxidation of -SH groups). Iodoacetamide is commonly used to block cysteines and increase ionization efficiencies in MALDI-MS applications. Iodoacetamide is conveniently packaged for single-use high throughput applications.

    Package Sizes: 5x10 mg tubes, 20x10 mg, 100 mg and 1 gram

    Product Numbers: 14107-5x10, 14107-20x10, 14107-100, 14107-1

    Product Name: Iodoacetamide

  • Maleimide > 99%

    Maleimide (2,5-Pyrroledione) is compound with a wide range of synthetic and protein modification applications. 2,5-Pyrroledione is commonly utilized in synthetic applications and as a synthetic intermediate or starting material for numerous compounds. The double bond of Maleimide is reactive towards cysteines (-SH) and other thiol containing compounds. Maleimide (CAS# 541-59-3) can be used to block cysteine (-SH) residues, is useful in Diels-Alder reactions and Michael addition synthetic processes.

    CovaChem's chemists manufacture several Maleimide compounds, and knows first hand the importance of having this compound in a pure form. CovaChem's Maleimide is highly refined and is among the highest purity in the field, and is analyzed by gas chromatography with purity levels >99%. This product is competitively priced in our catalog sizes and in bulk format.

    Package Sizes: 5 grams and 25 grams (custom and bulk quantities also available)

    Product Numbers: 11306-5 and 11306-25

    Product Name: Maleimide >99%

    Alternative Names: 2,5-Pyrroledione; Maleimide


    Appearance: White Solid

    Purity: ≥ 99%

    Storage: 4 °C, protected from moisture


    Properties Physical State: Solid

    CAS#: 541-59-3

    Tariff Code: 2925.19.9100

    UN Number (IATA): 2923

    Chemical Formula: C4H3NO2

    Molecular Weight: 97.07 g/mol

    Melting Point: 91-93 °C (Lit)

    Additional Product Information:
    Maleimide Product Information Bulletin
  • N-Ethoxycarbonylmaleimide

    N-Ethoxycarbonyl maleimide (CAS# 55750-49-7) also known as N-Ethoxycarbonylmaleimide is used to introduce a maleimide group into the structure of a protein, peptide or amino acid. N-Ethoxycarbonylmaleimide can also be used to react with other amine containing compounds for the formation of a maleimide containing compound for later reactions with thiols (-SH). This compound is also useful for reactions involving Diel-Alder processes, Michael additions and other synthetic applications.
  • N-Ethylmaleimide (NEM)

    N-Ethylmaleimide (NEM) is a protein modifying chemical reagent used to protect sulfhydryl groups. N-Ethylmaleimide (NEM) is a useful reagent in protein research and in synthetic organic applications.
  • N-Methoxycarbonylmaleimide

    N-Methoxycarbonyl maleimide (CAS# 55750-48-6) also known as N-Methoxycarbonylmaleimide is a useful reagent for incorporating a a maleimide group into a protein, peptide, amino acid, or other amine containing molecule. N-Methoxycarbonyl maleimide is also used as a synthetic intermediate or starting material in reactions such as Diels-Alder and Michael additions.
  • N-succinimidyl-S-acetyl-thioacetate (SATA)

    N-succinimidyl-S-acetyl-thioacetate (SATA) is a protein modification agent used to protect free amine residues in proteins and peptides. SATA serves as a both a protecting agent for amine groups and as a useful reagent for converting an amine to a sulfhydryl. This can be very useful when looking to obtain a more specific handle for further protein modification or conjugation.

    Once N-succinimidyl-S-acetyl-thioacetate (SATA) is conjugated with the protein or other amine containing compound, the protected amine is easily converted to an unprotected thiol (-SH) residue by the reaction with Hydroxylamine (CovaChem 13304).

    Package Sizes: 100 mg, 1 gram

    Product Numbers: 14102-100, 14102-1

    Product Name: SATA

    Alternative Names: N-succinimidyl-S-acetyl-thioacetate; SATA Protein Modifier; SATA; Lysine Protecting Agent; N-Succinimidyl (acetylthio)acetate, N-Succinimidyl S-acetylthioglycolate, S-Acetylthioglycolic acid NHS ester; CAS# 76931-93-6; S-Acetylthioglycolic acid N-hydroxysuccinimide ester


    Appearance: White to Off-White Solid

    Purity: is ≥ 92% by Quantitative NMR

    Storage: 4 °C, protected from moisture


    Properties Physical State: Solid

    CAS#: 76931-93-6

    Chemical Formula: C8H9NO5S

    Molecular Weight: 231.23

    International Shipping

    Tariff Code: 2930.90.9190

  • Sulfo-NHS Acetate

    Sulfo-NHS Acetate (Sulfosuccinimidyl acetate) is a water soluble, protein modification reagent used to irreversibly block lysine residues. Sulfo-NHS Acetate contains a primary amine reactive, Sulfo-NHS ester and a short chain acetate group (2.8 Å).

    Package Sizes: 100 mg, 1 gram

    Product Numbers: 14103-100, 14103-1

    Product Name: Sulfo-NHS Acetate

    Alternative Names: Sulfo-NHS Acetate; Sulfo-NHS-Acetate; Sulfosuccinimidyl acetate; Acetic acid sulfosuccinimide ester; CAS# 152305-87-8


    Appearance: White to Off-White Solid

    Purity: is ≥ 92% by Quantitative NMR

    Storage: 4 °C, protected from moisture


    Properties Physical State: Solid

    CAS#: 152305-87-8

    Chemical Formula: C6H6NNaO7S

    Molecular Weight: 259.17


    TCEP Product Description

    Tris(2-carboxyethyl) phosphine (TCEP, also known as TCEP-HCL) is an odorless reducing agent frequently used to reduce cysteine-cysteine disulfide bonds in proteins and to reduce disulfide bonds in DTSSP (CovaChem 13304) or DSP (CovaChem 13303) crosslinked proteins. TCEP is also an excellent reagent of choice for the complete removal of disulfide containing biotinylation reagents, such as Sulfo-NHS-SS-Biotin (CovaChem 14207)

    TCEP is a potent and fast acting reducing agent, with effective sample reduction occurring in as little as 5 minutes at room temperature. This reagent is highly water soluble, can be used in a wide pH range (pH = 1.5-8.5), and is used in a variety of biological buffers. TCEP is compatible with most applications where disulfide reductions is required, and selectively reacts with S-S bonds, while remaining non-reactive towards other protein functional groups. TCEP usually does not need to be removed by desalting prior to further thiol (-SH) reactions, such as with Maleimide conjugation or reactions with Iodoacetyl reagents.

    Package Sizes: 1 gram, 5 grams, 25 grams, 100 grams

    Product Numbers: 11303-1, 11303-5, 11303-25, 11303-100

    Product Name: TCEP

    Alternative Names: TCEP; TCEP-HCl; TCEP Hydrochloride; Tris(2-carboxyethyl) phosphine HCl; CAS# 51805-45-9; C9H15O6P


    Appearance: White Solid

    Purity: is ≥ 99%

    Water Solubility: is ≥ 300 mg/mL

    Storage: 4 °C, protected from moisture


    Properties Physical State: Solid

    CAS#: 51805-45-9

    Chemical Formula: C9H15O6P

    Molecular Weight: 286.6

    Additional Product Information:
    TCEP HCl Product Information Bulletin