Synthetic Biology
Home / Services / By Technology / Protein Engineering Services / Protein Modification and Labeling Services / Protein Biotinylation Service / Chemical Biotinylation Services / Sulfhydryl-Reactive Biotinylation Services
Trusted by Leading Research & Pharma Institutions

Sulfhydryl-reactive Biotinylation

Site-specific cysteine labeling with highly selective maleimide chemistry. Stable thioether conjugation for your protein detection, purification, and assay development needs.

~1000:1 Selectivity
Stable Thioether
Multiple Spacers
Learn More

Trusted by leading research and pharmaceutical institutions

Harvard
Pfizer
MIT
Roche
Stanford
Merck

Why Choose Us

pH 6.5-7.5 optimal conditions
Multiple spacer arm options
HABA/ESI-MS verification
Expert consultation included

Maleimide Chemistry

Michael addition reaction with cysteine thiols

Quality Guaranteed

Mass spec and HABA assay verification

Flexible Options

C2, LC, PEG spacers available

Selectivity
1000:1
Overview Technology Specifications Workflow Applications FAQ

Why Choose Sulfhydryl-reactive Biotinylation?

Targeted cysteine labeling preserves protein function while enabling sensitive detection and efficient purification

High Selectivity

Maleimide chemistry reacts exclusively with thiol groups at pH 6.5-7.5, providing ~1000x selectivity over amines.

Function Preserved

Label at cysteine residues away from active sites to maintain full biological activity of your protein.

Stable Conjugation

Thioether bond formed between maleimide and cysteine is stable under physiological conditions.

Flexible Options

Multiple spacer arm lengths and cleavable linker options to optimize for your specific application.

Ready to Start Your Project?

Get a custom quote within 24 hours. Our team is ready to help optimize your biotinylation experiment.

Talk to Scientist

The Science of Maleimide-Thiol Biotinylation

Our sulfhydryl-reactive biotinylation service leverages the highly selective Michael addition reaction between maleimide and thiol groups

Reaction Mechanism

The maleimide group contains an electrophilic carbon-carbon double bond that undergoes nucleophilic attack by the thiol group of cysteine residues. This Michael addition creates a stable thioether bond with exceptional selectivity under mildly acidic to neutral conditions.

Optimal pH Range 6.5 - 7.5
Reaction Temperature 20-25°C or 4°C
Reaction Time 2-4 hours at RT
Selectivity (thiol vs amine) ~1000:1 at pH 7.0

The resulting thiosuccinimide linkage can undergo hydrolysis at elevated pH to form a stable maleamic acid derivative, preventing retro-Michael reactions.

Available Reagent Options

Biotin-C2-Maleimide Short spacer
Biotin-PEGn-Maleimide PEG2-11 units
BMCC-Biotin Cyclohexyl spacer
Iodoacetyl-LC-Biotin Haloacetyl
HPDP-Biotin Cleavable

Service Specifications

Comprehensive parameters for our sulfhydryl-reactive biotinylation service

Parameter Specification
Reaction Chemistry Maleimide-thiol Michael addition
Optimal pH 6.5 - 7.5
Protein Scale 0.5 mg - 100+ mg
Degree of Labeling 1-5 biotins per protein (adjustable)
Spacer Arm Options C2, LC, PEG2, PEG4, PEG11
Cleavable Options HPDP-Biotin (disulfide cleavage)
Purification Method Size-exclusion chromatography (SEC)
Quality Control HABA assay, ESI-MS, SDS-PAGE
Deliverables Biotinylated protein, COA, MS report
Documentation Full protocol, analytical data, stability info

Our Streamlined Process

From protein submission to verified delivery in four simple steps

1

Feasibility Assessment

Evaluate protein structure, identify accessible cysteines, and select optimal labeling conditions.

2

Conjugation Reaction

Controlled maleimide-thiol reaction under optimized pH and temperature conditions.

3

Purification

SEC purification to remove excess biotin reagent and ensure high purity product.

4

QC & Release

HABA assay, mass spectrometry verification, and activity testing before shipment.

Applications

Diverse Applications Across Biotechnology

Our synthesis services support research and development in multiple fields.

Detection & Quantification

Biotinylated proteins can be detected with exceptional sensitivity using streptavidin-enzyme conjugates in various assay formats.

  • Western blotting with HRP/AP conjugates
  • ELISA development and optimization
  • Flow cytometry surface staining
  • Immunohistochemistry

Key Advantages

Detection limit Sub-ng level
Signal amplification Streptavidin binding
Compatibility Multiple formats

Affinity Purification

Leverage the ultra-high affinity of biotin-streptavidin interaction for efficient protein and protein complex enrichment.

  • Pull-down assays for interaction studies
  • Protein complex isolation
  • Multi-step purification workflows
  • Endogenous protein capture

Binding Affinity

Kd (biotin-streptavidin) ~10^-15 M
Elution options Native or denaturing
Reusability Yes (denaturing)

Surface Immobilization

Oriented protein immobilization on streptavidin-coated surfaces ensures maximum accessibility and activity retention.

  • Biosensor development (SPR, BLI)
  • Microarray spot preparation
  • Sensor chip functionalization
  • Controlled orientation immobilization

Surface Formats

Coating options Streptavidin, NeutrAvidin
Surface types Gold, glass, polymer
Orientation Site-specific (cysteine)

Diagnostic Development

Biotinylated proteins serve as key components in diagnostic assay platforms requiring stable, oriented capture elements.

  • Lateral flow assay development
  • ELISA kit manufacturing
  • Multiplex assay platforms
  • Point-of-care diagnostics

Quality Attributes

Batch consistency DOL verified
Stability Validated shelf life
Documentation GMP available

What Our Customers Say

Trusted by leading researchers and companies worldwide

The site-specific biotinylation preserved our enzyme's activity perfectly. We've switched all our SPR experiments to this service.

Senior Scientist

Biotechnology Company

Excellent batch-to-batch consistency for our diagnostic kit manufacturing. The QC documentation is comprehensive and regulatory-friendly.

Research Director

Pharmaceutical Company

The technical team helped us optimize the labeling conditions for our challenging membrane protein. The PEG-spacer option was key.

Principal Investigator

Academic Research Institution

Scientific Literature

Key publications supporting our sulfhydryl-reactive biotinylation service

45 Citations

Thiol-Cleavable Biotin for Chemical and Enzymatic Biotinylation and Its Application to Mitochondrial TurboID Proteomics

Haorong Li, Ashley M. Frankenfield, Ryan Houston, Shiori Sekine, Ling Hao (2021)

Journal of the American Society for Mass Spectrometry

View DOI
89 Citations

Fast Cysteine Bioconjugation Chemistry

Fa-Jie Chen, Jianmin Gao (2022)

Chemistry - A European Journal

View DOI
78 Citations

Biotin as a Reactive Handle to Selectively Label Proteins and DNA with Small Molecules

Adam D. Cotton, James A. Wells, Ian B. Seiple (2022)

ACS Chemical Biology

View DOI
12 Citations

Biotinylation Techniques for Labeling Proteins

BenchChem Technical Team (2024)

BenchChem Technical Reports

View DOI
18 Citations

In-depth Technical Guide to the Chemical Reaction Between Biotin-C2-maleimide and Cysteine

BenchChem Technical Team (2024)

BenchChem Technical Reports

View DOI

Frequently Asked Questions

Common questions about our sulfhydryl-reactive biotinylation service

What is the optimal pH for maleimide-thiol biotinylation?
The optimal pH range is 6.5-7.5. Within this window, the thiol group is sufficiently nucleophilic to react efficiently with the maleimide, while minimizing competing side reactions with amine groups. At pH 7.0, the reaction with thiols is approximately 1,000 times faster than with amines.
How do I prepare my protein for sulfhydryl-reactive biotinylation?
Ensure your protein is in an amine-free buffer (such as PBS) at pH 6.5-7.5. If your protein contains disulfide bonds, reduce them with TCEP before labeling, then remove excess TCEP via desalting. Avoid buffers containing DTT, beta-mercaptoethanol, or other reducing agents during the labeling reaction.
What molar ratio of biotin reagent to protein should I use?
A molar excess of 10-20:1 (biotin reagent to protein) is typically recommended for complete labeling. For peptides, a 1:1 to 5:1 ratio may be sufficient. The optimal ratio depends on the number of accessible thiol groups and your desired degree of labeling. Our team can help optimize conditions for your specific protein.
Can I achieve reversible biotinylation?
Yes, we offer HPDP-Biotin, which contains a disulfide bond in the spacer arm. This allows cleavage of the biotin-protein linkage using reducing agents like DTT or beta-mercaptoethanol, enabling recovery of the unmodified protein after purification or interaction studies.
How is biotinylation efficiency verified?
We use multiple methods for verification: HABA assay for quantitative biotin content determination, ESI-MS for mass confirmation of successful conjugation, and SDS-PAGE with streptavidin-HRP detection. All analytical data is included in your delivery documentation.
What spacer arm options are available?
We offer multiple spacer arm lengths to optimize for your application: C2 (short), LC (long chain), and various PEG lengths (PEG2, PEG4, PEG11). Longer spacers reduce steric hindrance and improve streptavidin accessibility, especially important for detection and SPR applications.

Ready to Start Your Project?

Get a customized quote for your Sulfhydryl-Reactive Biotinylation Services project. Our experts will respond within 24 hours.

No obligation
24h response
Expert consultation

Recommended Services

· Amine-Reactive Biotinylation Services
· Carboxyl-Reactive Biotinylation Services

Related Resources

· Cost and Efficiency Analysis of CRlSPR-Cas9 Knockout Services in Mice and Cell Lines
· Validating CRISPR Knockouts: Best Practices for qPCR, Sequencing, and Functional Assays
· Step-by-Step Guide to Generating CRISPR Knockout Cell Lines for Research
Quick Links

Home

Products

Services

About Us

Contact Us

Follow Us
CONTACT US

USA

Tel:

Email:

Japan

Tel:

Email:

Korea

Tel:

Email:

Copyright © 2026 CD Biosynsis. All rights reserved.