Product manual
Product use, preparation, operating conditions and storage.
BODIPY 650-665-XReactive dye
BODIPY 650-665-X Maleimide
Cat. No.QH-40-4007(Maleimide)
Label proteins and peptides with accessible cysteine, or thiol-modified molecules, through maleimide–thiol coupling.
Packs & quoteMaleimide
Thiol-reactive endR–SH
Free thiolC–S–R
Thioether linkageExcitation646 nm
Emission660 nm
TargetAccessible free thiols
Preparation and storage
- Storage
- Store at -20°C, protect from light and moisture
Thiol addition
Maleimide adds to a free thiol to form a thioether-containing product. Sulfur in disulfide bonds is not an available free thiol; reduction must preserve the required sample structure and function.
Cysteine labeling
For proteins and peptides with exposed free cysteine residues. Site availability depends on the actual thiol state.
Thiol-modified samples
For thiolated antibodies, nucleic acids or materials, with integrity assessed after pretreatment.
Filters and excitation leakage
Check filter bandwidths, dichroics and blocking against the actual excitation and emission values. Some BDP products have closely spaced peaks; peak positions alone do not establish excitation leakage or background. Check with unstained and free-dye controls.
Specifications
Product information
- Product name
- BODIPY 650-665-X Maleimide
- Cat. No.
- QH-40-4007(Maleimide)
- Product form
- Maleimide
- Target
- Accessible free thiols
- Pack sizes
- 1 mg / 5 mg / 10 mg / 25 mg / 100 mg
Preparation and properties
- Excitation wavelength
- 646 nm
- Emission wavelength
- 660 nm
- Molar extinction coefficient
- 102,000 M⁻¹ cm⁻¹
- Quantum yield
- 0.52
- Storage
- Store at -20°C, protect from light and moisture
Spectral information and detection
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
Thiol state
Determine whether thiols are oxidized, protected or buried. If reduction is needed, assess fragmentation, aggregation and function on a small sample.
Reductants and buffer
DTT and β-mercaptoethanol consume maleimide; residual TCEP can also interfere. Remove reductants by a validated procedure and label promptly.
Aqueous dilution and vessel adsorption
Confirm the supported solvent and stock concentration for the catalog number before diluting into a small sample. Check precipitation, vessel staining and transfer loss, matching final solvent fraction and vessel material when comparing conditions.
Prepare accessible thiols
Measure or assess free thiols and transfer the sample into a suitable buffer without competing thiols.
Couple protected from light
Set a dye series based on thiol molarity. Record pH, temperature and time, and check for precipitation or aggregation.
Purification and analysis
Select desalting, size-exclusion separation, dialysis or chromatography for the sample size. Remove free reagent before measuring concentration, labeling density and function. Residual free dye raises background and biases labeling-density calculations.
Check storage stability
Compare signal, background and function before and after storage. Free-thiol environments can affect the stability of some adducts.
Request product documentation
Select a document and enter your phone and email. Include the lot number for a CoA.
BODIPY 650-665-X MaleimideQH-40-4007(Maleimide)
Spectra and measurement conditions
Spectra, measurement conditions and detection settings for the exact catalog number.
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
Unlabeled sample
Use an unlabeled aliquot from the same preparation to assess changes in function, aggregation and recovery.
Free dye and negative sample
Include free-dye or no-target-handle controls to distinguish conjugation from adsorption. Match exposure, gain or voltage during detection.
Input titration
Compare a molar input series and assess signal, negative background, product recovery and function together.
Composition after purification
Check conjugate and free-dye fractions together. A clear or strongly fluorescent solution still needs suitable chromatography, electrophoresis or mass spectrometry to establish coupling; assess binding or enzyme activity separately for protein conjugates.
Technical articles
Thiol status and reduction pretreatment
Cysteines may be disulfide-bound or protected. Confirm free thiols before deciding on reduction.
For maleimide reactive dyes; first establish accessible thiols on the sample.
Reductant handling before maleimide labeling
DTT and β-mercaptoethanol compete for maleimide; residual TCEP can also interfere.
For maleimide routes; assess reductant carryover and removal.
Application support
Include your sample, formulation and detection method when requesting application guidance.
References
BODIPY dyes and their derivatives: syntheses and spectroscopic properties
Loudet A, Burgess K. · Chemical Reviews · 107(11):4891–4932 · 2007
Reviews BODIPY synthesis, derivatization and spectroscopic properties as background for distinguishing members of the dye family.
DOI: 10.1021/cr078381n
Reaction of Tris(2-carboxyethyl)phosphine (TCEP) with maleimide and alpha-haloacyl groups: anomalous elution of TCEP by gel filtration
Shafer DE, Inman JK, Lees A. · Analytical Biochemistry · 282(1):161–164 · 2000
Examines TCEP interactions with reactive groups, informing evaluation of reductant carryover and buffer exchange.
Tunable degradation of maleimide-thiol adducts in reducing environments
Baldwin AD, Kiick KL. · Bioconjugate Chemistry · 22(10):1946–1953 · 2011
Studies exchange reactions of model adducts in thiol-containing environments to inform conjugate stability assessment.
DOI: 10.1021/bc200148v
Frequently asked questions
Does the presence of cysteine ensure labeling?
No. Disulfides, protecting groups and buried sites can prevent reaction. Confirm accessible free thiols.
Can DTT remain in the reaction?
DTT competes for maleimide and should be removed before labeling using a suitable method.
Must the whole antibody be reduced?
Reduction depends on the intended sites. Excess reduction can damage antibody integrity; assess free-thiol content together with function.
Are BDP, X forms and WGA conjugates interchangeable?
Distinguish structure and purpose. X belongs to the specific product’s linker structure; WGA is an already labeled lectin. Use the exact catalog number’s preparation and workflow rather than inferring membrane permeability or equal solubility from the family name.