Product manual
Product use, preparation, operating conditions and storage.
Linkers and crosslinkersCrosslinking reagent
N-Ethylmaleimide(NEM)
Cat. No.QH-70-7006
Block accessible free thiols to control residual thiol reactivity during sample processing.
Packs & quoteDefine the sequence
Validate at small scale
Separate and proceed
Product formMaleimide
TargetAccessible free thiols
Preparation and storage
- Storage
- Store at -20°C, protect from light and moisture
Thiol blocking
NEM adds to a free thiol through maleimide chemistry, consuming the site. It is a thiol blocker rather than a fluorescent dye and should not precede a reaction that needs the same thiol.
Control thiol reactivity
Block accessible free thiols to control residual thiol reactivity during sample processing.
Product and functional assessment
Remove excess NEM when needed and assess remaining thiols and sample function.
Specifications
Product information
- Product name
- N-Ethylmaleimide(NEM)
- Cat. No.
- QH-70-7006
- Product form
- Maleimide
- Target
- Accessible free thiols
- Pack sizes
- 50 mg / 100 mg / 250 mg
Preparation and properties
- CAS
- 128-53-0
- Storage
- Store at -20°C, protect from light and moisture
Product parameters
Use parameters for the exact catalog number when preparing reagents, setting reagent input or calculating results. Request a lot-specific CoA for test results.
Protocol
Pre-reaction checks
Choose addition order for the objective; functional cysteine residues may also be blocked.
Solvent and molar calculation
Select solvent for this structure, salt form and solubility. Calculate molar inputs from its molecular weight; equal masses of different linkers are not equimolar.
Define the sequence
Add at the stage where thiol reactivity should be stopped or blocked, checking whether later steps still require free thiols.
Validate at small scale
Choose addition order for the objective; functional cysteine residues may also be blocked.
Separate and proceed
Remove excess blocker when required before functional or downstream analysis.
Assess the outcome
Remove excess NEM when needed and assess remaining thiols and sample function.
Request product documentation
Select a document and enter your phone and email. Include the lot number for a CoA.
N-Ethylmaleimide(NEM)QH-70-7006
Certificate of analysis (CoA)
Lot-specific test results. Include the lot number from the vial.
Safety data sheet (SDS)
Handling, storage and emergency response information.
Quality and lot information
Untreated sample
Compare integrity and function with an untreated aliquot from the same preparation.
Reaction-pair control
Compare available thiols before and after blocking to verify the required extent.
References
Thermo Fisher · Sulfhydryl-reactive chemistry
thermofisher.com
Explains thiol addition, blocking and disulfide exchange; maleimide, NEM, SPDP and Traut’s reagent have different purposes and products.
Frequently asked questions
Can NEM be added before a thiol-labeling step?
NEM adds to a free thiol through maleimide chemistry, consuming the site. It is a thiol blocker rather than a fluorescent dye and should not precede a reaction that needs the same thiol.
Does this reagent itself provide fluorescence?
It is used for coupling, modification, blocking or biotin deposition. Fluorescence requires a suitable fluorophore or detection system.
Can another linker’s conditions be reused?
Reactive ends, spacers, salt form and solubility can differ. Establish a small-scale reaction with this reagent and analyze the product.
How is the intended outcome confirmed?
Remove excess NEM when needed and assess remaining thiols and sample function.