Description

Eosin Maleimide CAS NO 76296-42-9 is a fluorescent thiol-reactive probe, widely used as a labeling reagent for proteins, peptides, and other biomolecules. Its core value lies in its ability to form stable thioether bonds with cysteine residues, enabling sensitive detection and analysis in complex biological systems. This compound is essential for researchers and manufacturers in the fields of bioconjugation, proteomics, diagnostic assay development, and fluorescence microscopy.

Application

• Protein Labeling & Bioconjugation: Covalent attachment to cysteine-containing proteins for tracking, purification, or functional studies.
• Fluorescence-Based Assays: Development of diagnostic kits and high-throughput screening (HTS) assays utilizing its bright fluorescence.
• Proteomics Research: Tagging of peptides and proteins for mass spectrometry analysis or gel-based detection methods.
• Cell Biology & Microscopy: Labeling of intracellular proteins for live-cell or fixed-cell imaging applications.
• Antibody-Drug Conjugate (ADC) Research: Used as a model linker-payload in the development and characterization of novel ADC constructs.
• Sensor Development: Integration into chemical sensors and biosensors for the detection of specific analytes.

Basic Information

Product Name	Eosin Maleimide
CAS No.	76296-42-9
Molecular Formula	C24H12Br4N2O9
Molecular Weight	827.88 g/mol
Synonyms	Eosin-5-maleimide; 2',4',5',7'-Tetrabromo-3',6'-dihydroxy-3-oxospiro[isobenzofuran-1(3H),9'-[9H]xanthene]-5-carboxamide, N-(2,5-Dihydro-2,5-dioxo-1H-pyrrol-1-yl)-; 5-((2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)carbamoyl)eosin; Eosin 5-maleimide; 5-Eosinmaleimide
EINECS	Contact for details

Quality Control

Our Eosin Maleimide is produced under strict quality management protocols. Each batch undergoes comprehensive analytical testing, including HPLC for purity and identity confirmation, to ensure it meets the high standards required for life science research. A Certificate of Analysis (COA) detailing specific results for purity, absorbance, and fluorescence properties is provided with every shipment.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry place at 15-25°C. The product is light-sensitive and should be handled under appropriate conditions to prevent degradation.

Specification

Item	Specification
Appearance	Red to reddish-brown powder
Identification (HPLC/UV-Vis)	Conforms
Purity (HPLC)	≥95.0%
Absorbance (λmax)	~525-530 nm
Extinction Coefficient (ε)	~90,000 - 100,000 M-1cm-1
Solubility	Soluble in DMSO, DMF; sparingly soluble in water

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.