Cryo-EM 3D Structure-Enabled Antibody Development

Unlock the fundamentals of your protein. We tackle targets that are difficult to crystalize – including large assemblies or membrane proteins.

3D Structure Based Answers that Drive Decision Making in Antibody Development

Antibody development increasingly depends on understanding how molecules interact in 3D, not just whether or with what affinity they bind. Traditional methods to map antibody-antigen interactions provide indirect, low-resolution or often ambiguous insights, leaving critical questions unanswered at the moments that matter most:

Lead selection, mechanistic validation, and go/no-go decisions.

Cryo-EM closes this gap by directly visualizing antibody–antigen interaction in native conditions, delivering high-confidence answers on binding mode, epitope specificity, and conformational changes.

With ATEM’s high-throughput 3D Epitope Mapping workflow, these structural answers reach your team early in development, not only after a final candidate has been selected. The result: critical decisions can be backed by structural evidence, so you can advance to your next project milestone with confidence.

Structure-Driven Decisions in Antibody Development

Cryo-EM 3D Epitope Mapping data transforms empirical structural insights into clear development decisions, reducing ambiguity and iteration cycles while identifying the best lead candidate from a given lead series.

Lead Selection & Portfolio Strategy

Select lead and backup candidates that bind structurally diverse epitopes or specific regions or moieties on the antigen.

Identify epitope overlap and redundancy across candidates, insights far beyond of what is possible to achieve with affinity-based assays.

Strengthen IP positioning through unambiguous 3D epitope differentiation

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Lead Candidate Differentiation

Characterize lead candidates that may have similar affinity but different binding modes

Distinguish functional vs. non-functional binding

Select lead candidates that bind close to or away from certain antigen moieties (i.e. glycosylation sites, membrane anchors, phosphorylation or dimerization sites, other functionally relevant areas, etc…)

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Mechanism of Action (MoA) Validation

Confirm binding architecture of your antibody-antigen complex and deduce the biological mechanism of your lead candidates

Identify important conformational effects (i.e. the structural arrangement) on the antigen

Determine whether a monomer or multimer of the antigen is bound by the candidate

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Development Risk Reduction

Detect suboptimal binding configurations early

Avoid late-stage failure due to structural incompatibility or steric clashes in-vivo

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Rational Design & Optimisation

Guide rational antibody engineering at residue level

Rationally design bispecific formats by selecting candidates with ideal binding geometries

Validate AI-designed antibodies experimentally

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Regulatory & Translational Support

Support IND-enabling studies with high-quality structural evidence

Improve interpretation of in vivo and in silico data

Strengthen confidence in candidate progression

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Make Effective Decisions From Both Intermediate and High Resolutions

Intermediate
Resolution

Epitope Mapping

Define the epitope area of interacting amino acids (linear and conformational epitopes). For multiple Fabs, define epitope overlap/distinctiveness.

Paratope Mapping
Antigen Conformation Changes

Define the conformation of the protein-antibody at secondary structure level and understand and compare the effects of different antibodies.

Post- translational Modifications

Visualize highly ordered, bulky post-translational modifications such as glycosylation or ubiquitylation.

High
Resolution

Epitope Mapping

Define epitopes with single amino acid precision (linear and conformational epitopes).

  • Better interpret in-vivo/silico results.
  • Identify potential challenges – e.g. exclude unfavorable regions.
  • Support IND submissions.
  • Validation of computational models.
    Mutation comparison of multiple protein-Fab complexes.
  • Computational experiments such as docking simulations.
Applications
Paratope Mapping

Potential mapping of paratopes at high resolutions.

  • Intellectual property and patent applications.
  • Antibody engineering – single amino acid substitutions.
  • MD simulation potential.
Applications
Antigen Conformation Changes

Compare conformational changes between samples at single amino acid precision.

  • Effects on amino acid accessibility on the target protein.
  • Changes in secondary structure induced by antibody binding.|
Applications
Post- translational Modifications

Visualize post-translational modifications such as glycosylation, phosphorylation, ubiquitylation with higher certainty.

  • Understand if/how post-translational modifications interact with the protein-antibody.
  • Find out if the presence of PTMs might influence protein binding (i.e. only binds phosphorylated).
Applications

Coverage Across Antibody Modalities

  • Lead selection and epitope differentiation
  • MoA validation and redundancy analysis
  • Enable rational design/maturation pathways
  • Geometry and bridging analysis
  • Synapse formation, steric and functional constraints
  • Target engagement and binding orientation
  • Payload positioning impact
  • Epitope accessibility and compact binding modes
  • AI-designed binder validation
  • Structural validation of predicted binding sites and modalities
  • RMSD and pose comparison vs. computational models

What you Get from ATEM’s 3D Epitope Mapping

ATEM delivers tiered 3D structural insights, from precisely determined epitope residues to functional MoA interpretation to directly support development decisions.

Results are delivered in standardized reports (i.e. PDF + Excel + 3D models) for cross-functional easy access.

Primary Structural Readouts

Structural Context

Comparative & Population-Level Insights

Decision & Interpretation Layer

Advantages of Cryo-EM in Antibody Development

Cryo-EM uniquely combines 3D structural resolution, throughput, and native-state analysis, addressing the most relevant limitations of traditional methods.

Compared to HDX-MS / Alanine Scanning

Unique Advantages of ATEM’s Cryo-EM Platform

Compared to X-ray Crystallography

Method Comparison for Epitope Mapping

Intermediate Resolution – High(er) Throughput and Budget Efficiency

Cryo-EM Medium Resolution
HDX-MS
Alanine Scanning
Resolution
4 – 10 Å
Resolution
10 – 30 Å
Resolution
-
Analysis of Confor­mational Dynamics
Major Structural States
Analysis of Confor­mational Dynamics
High
Analysis of Confor­mational Dynamics
Not at All
Sample Preparation
Label Free
Sample Preparation
Labeled
Sample Preparation
Labeled
Result Confidence
High
Result Confidence
Medium
Result Confidence
Low
Results
Epitope
Results
Epitope Region
Results
Epitope Region
Type of Antibodies
All (Fab preferred)
Type of Antibodies
All
Type of Antibodies
All
Readout
3D Structural Model
Readout
Peptide Map
Readout
“Hotspot” Residues
Complex Size
Suitable for complexes > 60 kDa
Complex Size
Larger sizes less viable
Complex Size
Larger targets require domain focus
Challenges
  • Sample preparation
  • Preferred orientation
  • Particle heterogeniety
Challenges
  • Risk of low accuracy due to back-exchange Incomplete digestion
  • Difficulty to resolve flexible regions
  • Masking due to post-translational modifications
Challenges
  • Risk of false positives/negatives
  • Labor-intensive
  • Mutations can alter protein folding and indirectly lead to loss of binding or false positives
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High-Resolution
Methods

Cryo-EM High-Resolution
X-Ray Crystallography
Resolution
2.5 – 4 Å
Resolution
1.5 - 3.5 Å
Analysis of Conformational Dynamics
Major Structural States
Analysis of Conformational Dynamics
High
Sample Preparation
Label Free
Sample Preparation
Crystallization
Result Confidence
Very High
Result Confidence
Very High
Results
Epitope & Paratope
Results
Epitope & Paratope
Type of Antibodies
All (Fab preferred)
Type of Antibodies
Fabs
Readout
3D Structural Model
Readout
3D Structural Model
Complex Size
Suitable for complexes > 60 kDa
Complex Size
Challenging for large complexes preferred for small complexes.
Challenges
  • Sample preparation
  • Preferred orientation
  • Particle heterogeniety
Challenges
  • Failure of crystallization
  • Post-translational modifications can lower crystallization possibilities
  • Non-native conditions may affect epitope conformation
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Sample Requirements for Cryo-EM Analysis

To initiate a cryo-EM epitope mapping project, only a limited set of inputs is required.

Required Materials

Typical Requirements

Conditions

NOT Required

Cryo-EM does noet require crystallisation, labelling or extensive sample engineering.

Cryo-EM Workflow from Sample to Decision

1. Pilot Phase

Feasibility & Sample Assessment

  • Sample material quality, stability and homogeneity assessment
  • Biochemical complex formation optimization
  • Cryo-EM grid preparation optimization screening
  • Cryo-EM dataset collection and 2D Target Complex analysis
  • Feasibility validation (2 weeks)
1. Pilot Phase
2. Intermediate Resolution Phase

3D Epitope & Mode of Action Insights

  • 3D reconstruction of Target Complex (4–10 Å)
  • Epitope mapping and comparative structural analysis
  • Rigid body fitting of available atomic coordinate models (PDB format)
2. Intermediate Resolution Phase
3. High Resolution Phase (Optional)

3D Epitope, Paratope, Mode of Action & IP relevant Insights at sidechain level

  • High-resolution data collection and refinement (<4 Å)
  • Detailed epitope and paratope mapping
  • Atomic coordinate model building and refinement (PDB format)
3. High Resolution Phase (Optional)
4. Reporting & Delivery

Decision Enablement

  • Comprehensive, non-structural biologist friendly reporting
  • Standardized reporting (PDF, Excel, PDB, 3D models)
  • Cross-functional interpretation (R&D, CMC, IP)
  • Direct support for development decisions
4. Reporting & Delivery