Description

Eosin-5-Maleimide is a high-purity, bifunctional fluorescent probe and labeling reagent widely used in biochemical research. Its core value lies in its ability to covalently bind to sulfhydryl (-SH) groups on proteins and peptides, enabling sensitive detection, quantification, and imaging. This compound is essential for researchers and manufacturers in the fields of bioconjugation, protein chemistry, and diagnostic assay development.

Application

• Protein Labeling & Conjugation: Covalent tagging of cysteine residues in proteins for structural and functional studies.
• Biomolecular Assay Development: Used as a fluorescent tracer or detection reagent in ELISA, fluorescence polarization, and other immunoassays.
• Cell Biology & Imaging: Labeling of cell surface proteins or intracellular thiol-containing molecules for fluorescence microscopy and flow cytometry.
• Drug Discovery & Screening: Tool compound for studying protein-ligand interactions and enzyme activity assays.
• Diagnostic Kit Manufacturing: A key component in the production of fluorescent-based diagnostic tests and biosensors.
• Biophysical Research: Employed in fluorescence resonance energy transfer (FRET) studies to investigate molecular distances and interactions.

Basic Information

Product Name	Eosin-5-Maleimide
CAS No.	150322-02-4
Molecular Formula	C30H17Br2N3O9
Molecular Weight	723.18 g/mol
Synonyms	5-((2-(2,5-Dihydro-2,5-dioxo-1H-pyrrol-1-yl)ethoxy)carbonyl)eosin; Eosin-5-maleimide, SE; Eosin 5-isothiocyanate analog; 5-(((2-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)ethyl)carbamoyl)eosin; Fluorescent thiol-reactive probe; E5M
EINECS	Contact for details

Quality Control

Our Eosin-5-Maleimide is manufactured under strict quality management systems. Each batch undergoes rigorous analytical testing, including HPLC for purity and identity confirmation, to ensure it meets the high standards required for research and diagnostic applications. A comprehensive Certificate of Analysis (COA) detailing 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 2-8°C. This product is hygroscopic (moisture-sensitive) and should be kept under desiccant. Allow the vial to equilibrate to room temperature before opening to minimize moisture uptake.

Specification

Item	Specification
Appearance	Red to reddish-brown powder
Identification (HPLC/UV-Vis)	Conforms
Purity (HPLC)	≥ 95.0%
Absorbance (λmax)	~525-530 nm
Emission (λmax)	~545-550 nm
Water Content (KF)	≤ 3.0%
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.