How to use De Novo sequencing to analyze antibody structure?

De Novo sequencing refers to the process of deducing the amino acid sequence directly from proteins using MS/MS fragment ion data collected by high-resolution mass spectrometry in the absence of any database reference. The key to this technique lies in digesting the protein into numerous short peptide segments that can cover the entire sequence, analyzing these fragment spectra through algorithms, and subsequently performing sequence assembly to obtain the full-length sequences of antibody light and heavy chains. Compared to methods that rely on database matching, De Novo sequencing truly enables the ability to reconstruct the full sequence starting from the protein, making it particularly suitable for complex situations such as antibodies from natural sources, antibodies from animal immunization, antibodies from clinical samples, and antibody reconstruction where gene vectors have been lost.

 

1. Why is sequence information indispensable for antibody structure analysis?

Antibodies, as highly specific functional protein molecules, have their primary structure (amino acid sequence) determine antigen recognition capability, pharmacological mechanism, safety, and developability. Comprehensive analysis of antibody structure is fundamental to antibody drug development, vaccine research, functional reconstruction, expression system optimization, and consistency verification. In reality, researchers and companies often face antibody samples where only proteins are available, while genes are lacking, such as natural antibodies obtained from animal immunization, historical samples with lost expression vectors, or fluid antibodies in clinical samples. In these cases, traditional sequence acquisition methods relying on mRNA or reference databases fail, necessitating the use of mass spectrometry-drivenDe Novo sequencingto achieve comprehensive analysis of antibody structure.

 

2. What is the technical process of De Novo antibody sequencing?

1. Antibody sample preparation

Requirespurified antibody protein(such as SDS-PAGE bands, affinity purification products, concentrated supernatant). BioPharmTek supports sample pre-treatment, including Protein A/G enrichment, desalting, and concentration.

 

2. Multi-enzyme digestion and peptide preparation

Utilize multiple enzymes (Trypsin, Chymotrypsin, AspN, etc.) for parallel digestion, generatinga large number of overlapping peptide segmentsto improve coverage.

 

3. Mass spectrometry analysis (LC-MS/MS)

Utilize high-resolution mass spectrometers (such as Orbitrap Fusion Lumos) for MS/MS fragment acquisition, obtaining fragment ion spectra for each peptide segment.

 

4. De Novo sequence inference and assembly

Apply specialized algorithms (such as PEAKS, Novor) for sequence recognition and reconstruct the complete light and heavy chain sequences through assembly logic.

 

5. Structure validation and functional modeling (optional)

Further sequence modeling, expression validation, or binding site prediction can be conducted for functional analysis or antibody engineering.

 

3. Challenges and strategies in the process of analyzing antibody structure

Antibody molecules have long sequences and complex structures, with critical functional regions (such as CDRs) exhibiting high variability, posing high requirements for coverage and accuracy in De Novo sequencing. Firstly, CDR regions often have few cleavage sites and stable spatial structures, making it difficult for conventional enzymes to fully cleave them, resulting in data coverage blind spots. Therefore, a multi-enzyme digestion strategy is crucial, as it creates more overlapping fragments and enhances recognition ability from different angles. Secondly, the high homology between antibody light and heavy chains can lead to mismatches during assembly, requiring the introduction of structural template matching and manual review mechanisms for identification. Furthermore, antibodies naturally undergo post-translational modifications such as glycosylation, oxidation, and deamidation, which not only affect function but also lead to mass spectrometry peak shifts or even fragment loss. It is necessary to enable modification recognition functions in algorithms and combine them with manual verification. Overall, De Novo sequencing relies not only on hardware platforms but also on enzyme digestion design, data integration, structural analysis, and manual review system strategies.

 

4. Common application scenarios of De Novo antibody analysis

  

Application direction	Background description	De Novo sequencing
Old antibody reconstruction	Sequence lost but protein or activity retained	No
Clinical sample antibody analysis	Unable to extract mRNA, only antibody protein available	Unknown protein
Polyclonal antibody research	Extract core antibody sequences for expression validation	Can be fully captured
Antibody patent circumvention	Design new antibodies based on structural differences	PEAKS, Novor, pNovo
Antibody drug consistency verification	Compare products from different batches/expression systems	High (depends on experience and algorithms)

 

BioPharmTek Biotechnology: Professional De Novo antibody sequencing solutions

As a provider of mass spectrometry-driven protein structure analysis services, BioPharmTek Biotechnology has established a complete process coveringantibody sample preparation, multi-enzyme strategy design, high-precision mass spectrometry analysis, self-developed algorithm assembly, modification recognition, and recombinant expression validationWe employ the Orbitrap Fusion Lumos platform, combined with five different proteases for parallel digestion, generating a high-coverage data matrix; during data processing, we integrate PEAKS with proprietary algorithms and introduce manual verification and structural modeling mechanisms to effectively enhance the resolution accuracy of key segments such as CDR. We provide high-confidence, high-completeness De Novo antibody structure analysis services for universities, hospitals, and biopharmaceutical companies, supporting:

• Full-length antibody sequence reconstruction (including variable and constant regions)

• CDR high-coverage analysis and modeling

• Modification site annotation + differential comparison analysis

• Recombinant expression template design services

• Homologous antibody database comparison + functional annotation

In terms of delivery, we not only provide complete antibody sequences but also offer optional antibody modeling, recombinant expression template construction, and structural comparison reports with the original antibody, meeting various client needs from scientific exploration to drug development.

 

In today's world where antibody research and development are accelerating and data integrity requirements are increasing, De Novo antibody sequencing is transitioning from a 'premium option' to a 'fundamental capability.' It not only addresses the challenge of structural analysis for samples lacking genetic sequences but also provides technical support for consistency verification, functional reconstruction, patent design, and expression optimization of antibody drugs. Through high-precision mass spectrometry platforms, scientific enzymatic digestion design, and rigorous data analysis, Protai BioTech is dedicated to providing every client with expressible, verifiable, and translatable antibody sequence information. Whether you are a research team or an antibody drug company, we are willing to be your reliable partner on the path of antibody structural analysis. If you already have antibody samples but lack sequence information, feel free to contact Protai BioTech for a free sample evaluation and customized solution. We will use our expertise and experience to safeguard your project.

 

Protai BioTech – A leading service provider in the characterization of bioproducts and multi-omics mass spectrometry analysis.

 

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