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N-Ethylmaleimide (NEM) Cysteine Peptidases Inhibitor

Name: N-Ethylmaleimide (NEM)
Brand: Selleck Chemicals
SKU: S3692
Availability: InStock
Rating: 5 (17 reviews)

Cat.No.S3692

NEM (N-Ethylmaleimide) is an organic compound that is derived from maleic acid. It is an irreversible inhibitor of all cysteine peptidases, with alkylation occurring at the active site thiol group. N-Ethylmaleimide (NEM) inactivates endogenous deubiquitinating enzymes (DUBs). N-Ethylmaleimide (NEM) specifically inhibits phosphate transport in mitochondria.

Chemical Structure

Molecular Weight: 125.13

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Quality Control

Batch: Purity: 99.96%

99.96

Related Targets	HDAC Caspase Proteasome Secretase MMP HCV Protease Tyrosinase HIV Protease DPP Serine Protease
Other Cysteine Protease Inhibitors	MG132 SSS Calpeptin Aloxistatin (E-64d) Odanacatib E-64 MG-101 (ALLN) Z-FA-FMK Cathepsin Inhibitor 1 PD 151746 Loxistatin Acid (E-64C)

Cell Culture, Treatment & Working Concentration

Cell Lines	Assay Type	Incubation Time	Activity Description	PMID
KBV1	Cytotoxicity assay	72 hrs	Cytotoxicity against drug-resistant human KBV1 cells expressing P-gp incubated for 72 hrs by MTT assay, IC50=16μM	21657271
KB-3-1	Cytotoxicity assay	72 hrs	Cytotoxicity against human KB-3-1 cells incubated for 72 hrs by MTT assay, IC50=30μM	21657271
COS7	Function assay	90 mins	Binding affinity to rat Galpha-fused ORL1 receptor expressed in african green monkey COS7 cells after 90 mins, EC50=43.7μM	22061823
BL21 (DE3)	Function assay	30 mins	Irreversible inhibition of human recombinant IDE expressed in Escherichia coli BL21 (DE3) cells using ATTO 655- Cys-Lys-Leu-Val-Phe-Phe-Ala-Glu-Asp-Trp as substrate preincubated for 30 mins followed by 100 fold compound dilution by spectrophotometric anal	31276900
KU812	Function assay	20 mins	Inhibition of SENP1 in human KU812 cells preincubated for 20 mins followed by addition of HA-SUMO1-VS as substrate measured after 2 hrs by immunoblot analysis	27491710
Click to View More Cell Line Experimental Data

Solubility

In vitro
Batch:

DMSO : 25 mg/mL (199.79 mM)
(Moisture-contaminated DMSO may reduce solubility. Use fresh, anhydrous DMSO.)

Water : 25 mg/mL

Ethanol : 25 mg/mL

Molarity Calculator

Mass	Concentration	Volume	Molecular Weight
Mass value Mass unit	Concentration value Concentration unit	Volume value Volume unit	Molecular weight (g/mol)

Dilution Calculator Molecular Weight Calculator

In vivo batch selection In vivo Batch:
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.

In vivo Formulation Calculator (Clear solution)

Step 1: Enter information below (Recommended: An additional animal making an allowance for loss during the experiment)

Dosage: mg/kg

Average weight of animals: g

Dosing volume per animal: μL

Number of animals:

Step 2: Enter the in vivo formulation (This is only the calculator, not formulation. Please contact us first if there is no in vivo formulation at the solubility Section.)

% DMSO

% Tween 80

% ddH₂O

% DMSO

Calculation results:

Working concentration: mg/ml;

Method for preparing DMSO master liquid: mg drug pre-dissolved in μL DMSO ( Master liquid concentration mg/mL, Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug. )

Method for preparing in vivo formulation: Take μL DMSO master liquid, next addμL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH₂O, mix and clarify.

Method for preparing in vivo formulation: Take μL DMSO master liquid, next add μL Corn oil, mix and clarify.

Note: 1. Please make sure the liquid is clear before adding the next solvent.
2. Be sure to add the solvent(s) in order. You must ensure that the solution obtained, in the previous addition, is a clear solution before proceeding to add the next solvent. Physical methods such
as vortex, ultrasound or hot water bath can be used to aid dissolving.

Chemical Information, Storage & Stability

Molecular Weight	125.13	Formula	C₆H₇NO₂	Storage (From the date of receipt)	3 years-20°Cpowder
CAS No.	128-53-0	Download SDF		Storage of Stock Solutions	1 year-80°Cin solvent 1 month-20°Cin solvent
Synonyms	N/A			SMILES	CCN1C(=O)C=CC1=O

Read more about storage stability stock solution CAS number SMILES

Mechanism of Action

In vitro	N-Ethylmaleimide (NEM) inactivates endogenous deubiquitinating enzymes (DUBs) and specifically inhibits phosphate transport in mitochondria.
In vivo	N-Ethylmaleimide (NEM) is an irreversible cysteine protease (sulfhydryl) inhibitor.
References	[1] https://pubmed.ncbi.nlm.nih.gov/35320710/ [2] https://pubmed.ncbi.nlm.nih.gov/10416830/

Clinical Trial Information

(data from https://clinicaltrials.gov, updated on 2026-08-14)

NCT Number	Recruitment	Conditions	Sponsor/Collaborators	Start Date	Phases
NCT07766720	RECRUITING	Exercise-induced Muscle Soreness; Exercise-induced Joint Pain; Exercise-induced Joint Stiffness; Exercise-induced Cartilage Turnover	ESM Technologies, LLC	2026-02-01
NCT03769857	COMPLETED	Exercise-induced Joint Pain; Exercise-induced Joint Stiffness; Exercise-induced Joint Cartilage Turnover	ESM Technologies, LLC	2019-01-13
NCT04215198	COMPLETED	Exercise-induced Joint Pain; Exercise-induced Joint Stiffness; Exercise-induced Joint Cartilage Turnover	ESM Technologies, LLC	2018-09-20
NCT03679923	COMPLETED	Exercise-induced Joint Pain; Exercise-induced Joint Stiffness; Exercise-induced Joint Cartilage Turnover	ESM Technologies, LLC	2018-09-20
NCT02751944	COMPLETED	Exercise-induced Joint Pain Stiffness and Cartilage Turnover	ESM Technologies, LLC	2015-12
NCT01407991	TERMINATED	Enteral Tube Placement	Children's Hospital of Philadelphia	2011-07	PHASE2

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Handling Instructions

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