HOSU is N-Hydroxysuccinimide, commonly abbreviated as NHS or HOSu. It is widely used as a coupling additive and active-ester precursor in peptide synthesis, amide-bond formation and bioconjugation chemistry.

Unlike direct peptide coupling reagents such as HATU and PyBOP, NHS normally functions together with a carboxyl-activating reagent such as a carbodiimide. The resulting N-hydroxysuccinimide ester provides an activated carboxylic-acid derivative that can react with primary amines to form stable amide bonds.

Product Information

What Is N-Hydroxysuccinimide?

N-Hydroxysuccinimide is used to convert activated carboxylic acids into NHS esters. These activated esters are important synthetic intermediates because they can subsequently react with primary amino groups to produce stable amide bonds.

NHS chemistry is used extensively in peptide chemistry, organic synthesis, protein modification and bioconjugation because it provides a practical route from a carboxyl-containing molecule to an amine-reactive derivative.

NHS in Carbodiimide Coupling

Carbodiimides such as DCC, DIC and EDC activate carboxylic acids, but the initial activated intermediates can be unstable and may undergo competing reactions.

Addition of NHS allows formation of an NHS ester intermediate that can subsequently react with an amine. NHS is therefore more accurately described as a coupling additive or active-ester precursor rather than a direct replacement for HATU or PyBOP.

NHS Ester Formation

NHS esters are commonly prepared from carboxyl-containing molecules prior to reaction with primary amines. Substrates can include amino acids, peptides, fluorescent dyes, biotin derivatives, linker molecules, polymers and other functionalized compounds.

The resulting active ester can be generated in situ or prepared as an intermediate for subsequent conjugation chemistry.

NHS Ester Hydrolysis and Reaction Conditions

NHS esters are susceptible to hydrolysis, particularly in aqueous systems. Reaction efficiency therefore depends on water content, pH, temperature, solvent composition, substrate concentration and the lifetime of the activated intermediate.

When NHS chemistry is used for bioconjugation, the reaction environment should balance amine reactivity against hydrolysis of the active ester.

Applications in Peptide Synthesis

N-Hydroxysuccinimide can be used in:

• carbodiimide-mediated peptide coupling;

• preparation of amino-acid NHS esters;

• preparation of peptide NHS esters;

• solution-phase amide-bond formation;

• peptide-linker conjugation;

• installation of fluorescent labels or reporter groups;

• biotinylation and other peptide modification workflows.

Applications in Bioconjugation

NHS ester chemistry is one of the most widely used strategies for coupling carboxyl-containing molecules to primary amines. It is therefore commonly encountered in peptide labeling, protein labeling, fluorescent conjugation, biotinylation and preparation of functional biomolecule conjugates.

Purified conjugates generated using NHS chemistry may subsequently be used in receptor-binding assays, immunoassays, imaging studies, protein-interaction experiments, surface-functionalization workflows and other in vitro research applications.

HOSU itself is an upstream synthetic reagent and is not intended as a direct biological assay reagent.

HOSU / NHS vs HATU and PyBOP

HATU and PyBOP are direct peptide coupling reagents that activate carboxyl groups during peptide-bond formation.

HOSU/NHS generally plays a different role. It is used as an additive or precursor for formation of an activated NHS ester, often following carbodiimide-mediated carboxyl activation.

HATU, PyBOP and NHS therefore participate in related amide-bond-forming workflows but should not be treated as interchangeable reagents.

NHS vs Sulfo-NHS

NHS and Sulfo-NHS use related succinimidyl ester chemistry but are different compounds. Sulfo-NHS contains a charged sulfonate group that increases aqueous solubility and is frequently used in water-based protein and bioconjugation workflows.

Standard NHS is widely used in organic or mixed-solvent synthetic chemistry. Selection between NHS and Sulfo-NHS should therefore be based on substrate solubility, reaction medium and downstream conjugation requirements.

Handling and Procurement Considerations

N-Hydroxysuccinimide is a reactive laboratory reagent and should be handled according to the current product-specific Material Safety Data Sheet. Avoid unnecessary contact with skin and eyes and use appropriate laboratory personal protective equipment.

For reproducible NHS ester chemistry, reagent quality, moisture exposure and reaction conditions should be considered together with the selected activating reagent.

Product Documents

A Material Safety Data Sheet (MSDS) is available for this product to support laboratory handling, storage and safety assessment.

MSDS_HOSU_AS2006

Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.

Frequently Asked Questions

Is HOSU the same as NHS?

Yes. HOSU or HOSu refers to N-Hydroxysuccinimide, which is more commonly abbreviated as NHS.

What is NHS used for?

NHS is used to prepare activated NHS esters from carboxyl-containing compounds. These esters can subsequently react with primary amines to form amide bonds.

Is NHS a peptide coupling reagent?

NHS is more accurately described as a coupling additive and active-ester precursor. It is commonly combined with carbodiimide-mediated carboxyl activation.

What does an NHS ester react with?

NHS esters are commonly used to acylate primary amines, including amino groups in peptides, proteins and other amine-containing molecules.

Can NHS be used for peptide labeling?

Yes. NHS ester chemistry is widely used for fluorescent labeling, biotinylation, linker attachment and other peptide-conjugation applications.

Is NHS the same as Sulfo-NHS?

No. Sulfo-NHS contains an additional sulfonate group that improves aqueous solubility. The two reagents use related active-ester chemistry but are selected for different solvent and conjugation conditions.

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