Description

Eosin-5-Maleimide is a high-purity, fluorescent labeling reagent specifically engineered for the selective modification of sulfhydryl groups in proteins and peptides. This compound is critical for researchers and manufacturers requiring precise, covalent labeling for applications in biochemistry, bioconjugation, and diagnostic assay development. It is essential for industries focused on proteomics, antibody-drug conjugate (ADC) development, and the creation of advanced fluorescent probes and biosensors.

Application

• Protein Labeling & Bioconjugation: Primary reagent for covalently tagging cysteine residues in proteins, antibodies, and enzymes for tracking, purification, or functional studies.
• Proteomics Research: Used in fluorescence-based assays for studying protein structure, function, interactions, and folding dynamics.
• Antibody-Drug Conjugate (ADC) Development: Serves as a model linker-payload component or fluorescent tracer in the research and characterization of ADC constructs.
• Diagnostic Assay Development: Employed in the synthesis of fluorescent probes and labels for immunoassays (e.g., ELISA, lateral flow tests) and histochemistry.
• Cell Biology & Imaging: Useful for fluorescent labeling of cell surface proteins or intracellular thiols for microscopy and flow cytometry.
• Pharmaceutical Analysis: Acts as a derivatization agent in analytical methods for the detection and quantification of thiol-containing compounds.

Basic Information

Product Name	Eosin-5-Maleimide
CAS No.	75350-45-7
Molecular Formula	C30H19Br2N3O9
Molecular Weight	725.20 g/mol
Synonyms	5-((2-(Carboxycarbonyl)(3',6'-dihydroxy-2',4',5',7'-tetrabromo-3-oxospiro[isobenzofuran-1(3H),9'-[9H]xanthen]-5-yl)amino)ethyl)amino)-5-oxopentanoic acid; Eosin-5-maleimide, triammonium salt; 5-((2-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)ethyl)amino)-5-oxopentanoic acid, eosin derivative; Eosin maleimide; Fluorescent thiol-reactive probe
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 assessment and spectroscopic methods for identity confirmation, to ensure it meets the high standards required for research and bioconjugation applications. A comprehensive Certificate of Analysis (COA) detailing purity, identity, and other critical parameters is provided with every shipment.

Storage

Preserve in a tightly closed container, protected from light. Store at 2-8°C under desiccant. This product is light-sensitive (store away from light) and easily oxidized (store under inert atmosphere). For long-term storage, keep the container sealed under an inert atmosphere such as argon or nitrogen in a freezer (-20°C).

Specification

Item	Specification
Appearance	Red to reddish-brown powder
Identification (IR)	Conforms to structure
Purity (HPLC)	≥ 95.0%
Absorption Maximum	~525 - 530 nm
Emission Maximum	~545 - 550 nm
Solubility	Soluble in DMSO, DMF; sparingly soluble in water
Moisture Content (KF)	≤ 2.0%

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