Precision Bioconjugation Service

Site-Specific Enzymatic Labeling

Achieve absolute positional fidelity with enzyme-catalyzed bioconjugation. Attach fluorophores, biotin, PEG, and functional probes to your biomolecules with 100% site-specificity under mild physiological conditions.

100% Site-Specific

Mild Conditions

Defined Stoichiometry

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Trusted by researchers at leading institutions

MIT

Stanford

Johns Hopkins

Pfizer

Roche

Why Enzymatic Labeling

100% positional fidelity

Homogeneous conjugates

Activity preserved

Defined stoichiometry

Precision Targeting

Enzyme recognition ensures labeling only at intended sites

Biological Activity Preserved

Mild conditions maintain native protein structure

Controlled Stoichiometry

Precise 1:1 or 2:1 label-to-protein ratios

Conversion Rate

90%+

Service Overview

Why Choose Enzymatic Labeling?

Traditional chemical labeling creates heterogeneous mixtures with unpredictable label positions. Our enzymatic approach delivers homogeneous conjugates with absolute precision.

100% Positional Fidelity

Enzyme recognition ensures labeling occurs only at the intended site within the target motif, eliminating positional isomers and heterogeneity in your conjugate preparations.

Single, defined labeling position
No mixture of isomers
Consistent batch-to-batch quality

Biological Activity Preserved

Mild reaction conditions under neutral pH and physiological temperatures ensure your protein's native structure and function remain intact throughout the labeling process.

Neutral pH, 4-37C conditions
Aqueous buffer systems
No denaturation or aggregation

Defined Stoichiometry

Achieve precise 1:1 or 2:1 label-to-protein ratios essential for quantitative imaging and FRET studies.

LC-MS/MS Verification

Every conjugate undergoes high-resolution mass spectrometry to confirm site-specificity.

Flexible Label Options

From fluorophores to biotin, PEG, and custom probes with full compatibility.

Technology Platform

Our Enzymatic Labeling Platform

We employ a suite of biocatalytic tools to achieve precise, site-specific modifications tailored to your experimental needs.

Biotin Ligase System

The biotin ligase specifically recognizes a 15-amino acid AviTag sequence and attaches biotin with 100% regioselectivity at a single lysine residue.

BirA Enzyme In Vivo/In Vitro

Transpeptidase Platform

Engineered transpeptidase recognizes the LPXTG motif and catalyzes attachment of oligoglycine-linked probes to the protein C-terminus.

Sortase A Native Amide Bond

Methyltransferase Platform

Engineered methyltransferases transfer modified groups to specific DNA sequences, enabling reversible and rewritable labeling.

DNA Targeting Reversible

Quality Control

LC-MS/MS Peptide mapping for site verification

Intact Mass Expected mass shift confirmation

Activity Functional assay verification

COA Full documentation included

Available Labels

Fluorescent FITC, Cy3, Cy5, Alexa Fluor series

Biotin For pull-down and immobilization

PEG Polyethylene glycol linkers

Click Azide, alkyne, DBCO handles

Specifications

Service Specifications

Comprehensive options to meet your research and development needs.

Parameter	Specification
Labeling Sites	N-terminus, C-terminus, Internal sites, Glycosylation sites
Available Labels	Fluorophores, Biotin, PEG, Click handles
Enzyme Tags	AviTag (15 aa), LPXTG (5 aa), Custom motifs
Conversion Rate	90%+ labeling efficiency
Purity	95%+ by SDS-PAGE
Stoichiometry	Defined 1:1 or 2:1 ratio (DAR)
Reaction Conditions	Neutral pH, 4-37C, Aqueous buffers
Quality Control	LC-MS/MS, Intact mass, Activity assays

ISO 9001 Certified

90%+ Conversion

Catalyst-Free Products

Full QC Documentation

Workflow

Streamlined Process from Design to Delivery

Our proven 5-step workflow ensures quality and efficiency at every stage.

Consultation

Project scoping and strategy development with our technical team

Motif Engineering

Computational analysis and subcloning for optimal tag placement

Biocatalytic Reaction

Optimized enzyme-to-substrate ratios with 90%+ conversion monitoring

Purification

High-resolution separation and catalyst removal

Validation

LC-MS/MS verification and functional assays

Applications

Research Applications

Versatile solutions for diverse scientific needs.

Live-Cell Imaging

Site-specific labeling ensures fluorophores are positioned away from active sites and binding interfaces, preserving protein function while enabling high-resolution fluorescence microscopy, FRET studies, and single-molecule tracking.

Confocal microscopy

FRET assays

Single-molecule tracking

Therapeutic Development

Achieve homogeneous antibody-drug conjugates (ADCs) with precise drug-to-antibody ratios (DAR). Site-specific labeling maintains biological activity while enabling controlled payload attachment for improved therapeutic efficacy.

ADC development

Bispecific antibodies

Radiopharmaceuticals

Diagnostic Applications

Develop highly specific diagnostic reagents with consistent batch-to-batch quality. Site-specific labeling ensures uniform orientation for improved binding kinetics and detection sensitivity in immunoassays.

ELISA development

Lateral flow assays

Flow cytometry

Basic Research

Support your fundamental studies with precisely labeled biomolecules. From structural biology to biochemical characterization, our conjugates provide the consistency needed for reproducible research.

Structural biology

Binding studies

Protein-protein interactions

Testimonials

What Our Partners Say

Trusted by researchers worldwide for quality and reliability.

The site-specific labeling achieved a homogeneous product that eliminated our previous batch-to-batch variability issues. The conjugate retained full activity, which was critical for our FRET experiments.

Senior Scientist

Biotechnology Company

We needed precise DAR control for our ADC program. The enzymatic labeling approach delivered consistent 2:1 stoichiometry that significantly improved our therapeutic efficacy studies.

Research Director

Pharmaceutical Company

The technical team's expertise in motif design saved us months of optimization. They identified the optimal tagging strategy for our challenging membrane protein, which other services had declined to attempt.

Principal Investigator

Academic Research Institution

Scientific Literature

Scientific Foundation

Key publications supporting our enzymatic labeling technologies.

186 Citations

Site-Selective and Rewritable Labeling of DNA through Enzymatic, Reversible, and Click Chemistries

Andrew A Wilkinson, et al. ACS Central Science. 2020.

A new method combining methyltransferase-directed labeling with reversible acyl hydrazones and click chemistry for sequential DNA functionalization.

View DOI

95 Citations

Site-Specific Protein Labeling and Generation of Defined Ubiquitin-Protein Conjugates Using an Asparaginyl Endopeptidase

Maximilian Fottner, et al. JACS. 2022.

Genetic code expansion combined with AEP-mediated transpeptidation enables labeling at internal protein sites with minimal footprint.

View DOI

78 Citations

Direct N- or C-Terminal Protein Labeling Via a Sortase-Mediated Swapping Approach

Min Cong, et al. Bioconjugate Chemistry. 2021.

A novel one-step sortase-mediated approach for direct N-terminal protein labeling with near-quantitative yield.

View DOI

42 Citations

Recording Binding Information Directly into DNA-Encoded Libraries Using Terminal Deoxynucleotidyl Transferase

Lukas A Schneider, et al. JACS. 2023.

TdT-mediated polyadenylation recording enables direct capture of binding affinity information from DNA-encoded libraries.

View DOI

28 Citations

Template-independent synthesis and 3'-end labelling of 2'-modified oligonucleotides with terminal deoxynucleotidyl transferases

Leping Sun, et al. Nucleic Acids Research. 2024.

Systematic exploration of TdT activities for template-independent synthesis and labeling of xenobiotic nucleic acids.

View DOI

FAQ

Frequently Asked Questions

Find answers to common questions about our service.

What types of site-specific labeling do you offer?

We offer multiple enzymatic labeling strategies including N-terminal labeling, C-terminal labeling, and labeling at internal sites using biotin ligase (BirA), transpeptidase (Sortase), and methyltransferase platforms. We also support dual-labeling for applications requiring multiple modification sites.

How long does a typical project take?

Project timelines vary based on complexity. Standard projects typically range from 6-10 weeks, including consultation, motif engineering, biocatalytic reaction optimization, purification, and quality control validation. Complex projects with challenging targets may require additional time.

How do you verify site-specificity?

We use high-resolution LC-MS/MS peptide mapping to verify that labeling occurs only at the intended site. Intact mass spectrometry confirms the expected mass shift, and activity assays ensure the conjugate maintains functional integrity. Full documentation is provided with each delivery.

What labels can be attached?

We support a wide range of functional groups including fluorescent dyes (FITC, Cy3, Cy5, Alexa Fluor series), biotin, polyethylene glycol (PEG) linkers, click chemistry handles (azide, alkyne, DBCO), and custom probes. For specific requirements, please consult our technical team.

Do you provide protein expression services?

Yes, we offer integrated expression-to-labeling workflows. We can express your protein with the required enzymatic recognition motif in our optimized expression systems (E. coli, mammalian cells), then proceed directly to labeling. This integrated approach minimizes variability and maximizes final conjugate quality.

What is your conversion efficiency?

Our optimized enzymatic reactions consistently achieve 90%+ labeling conversion. We monitor reaction progress via HPLC and gel-shift assays to ensure high yields before proceeding to purification. The final product is thoroughly characterized to confirm expected stoichiometry.

Ready to Start Your Project?

Get a customized quote for your Site-Specific Enzymatic Labeling Services project. Our experts will respond within 24 hours.

No obligation

24h response

Expert consultation

Site-Specific Enzymatic Labeling

Why Enzymatic Labeling

Precision Targeting

Biological Activity Preserved

Controlled Stoichiometry

Why Choose Enzymatic Labeling?

100% Positional Fidelity

Biological Activity Preserved

Defined Stoichiometry

LC-MS/MS Verification

Flexible Label Options

Ready to Get Started?

Our Enzymatic Labeling Platform

Biotin Ligase System

Transpeptidase Platform

Methyltransferase Platform

Quality Control

Available Labels

Service Specifications

Streamlined Process from Design to Delivery

Consultation

Motif Engineering

Biocatalytic Reaction

Purification

Validation

Research Applications

What Our Partners Say

Scientific Foundation

Site-Selective and Rewritable Labeling of DNA through Enzymatic, Reversible, and Click Chemistries

Site-Specific Protein Labeling and Generation of Defined Ubiquitin-Protein Conjugates Using an Asparaginyl Endopeptidase

Direct N- or C-Terminal Protein Labeling Via a Sortase-Mediated Swapping Approach

Recording Binding Information Directly into DNA-Encoded Libraries Using Terminal Deoxynucleotidyl Transferase

Template-independent synthesis and 3'-end labelling of 2'-modified oligonucleotides with terminal deoxynucleotidyl transferases

Frequently Asked Questions

Ready to Start Your Project?

Recommended Services

Related Resources

Request a Quote

Site-Specific Enzymatic Labeling

Why Enzymatic Labeling

Precision Targeting

Biological Activity Preserved

Controlled Stoichiometry

Why Choose Enzymatic Labeling?

100% Positional Fidelity

Biological Activity Preserved

Defined Stoichiometry

LC-MS/MS Verification

Flexible Label Options

Ready to Get Started?

Our Enzymatic Labeling Platform

Biotin Ligase System

Transpeptidase Platform

Methyltransferase Platform

Quality Control

Available Labels

Service Specifications

Streamlined Process from Design to Delivery

Consultation

Motif Engineering

Biocatalytic Reaction

Purification

Validation

Research Applications

What Our Partners Say

Scientific Foundation

Site-Selective and Rewritable Labeling of DNA through Enzymatic, Reversible, and Click Chemistries

Site-Specific Protein Labeling and Generation of Defined Ubiquitin-Protein Conjugates Using an Asparaginyl Endopeptidase

Direct N- or C-Terminal Protein Labeling Via a Sortase-Mediated Swapping Approach

Recording Binding Information Directly into DNA-Encoded Libraries Using Terminal Deoxynucleotidyl Transferase

Template-independent synthesis and 3'-end labelling of 2'-modified oligonucleotides with terminal deoxynucleotidyl transferases

Frequently Asked Questions

Ready to Start Your Project?

Recommended Services

Related Resources