Recombinant Protein Services
Overview
QYAOBIO provides recombinant protein expression and purification services across three expression platforms — E. coli, mammalian (HEK293, CHO), and yeast (Pichia pastoris) systems. We handle the full workflow from gene synthesis and codon optimization through expression, purification, and quality characterization. Our services support structural biology, drug discovery, immunology, and enzyme research programs.
All proteins are manufactured for research use only.
Selecting the Right Expression System
The choice of expression system is the single most important decision in a recombinant protein project. E. coli delivers speed and high yields but lacks the machinery for complex post-translational modifications. Mammalian cells produce proteins with native folding and full glycosylation, at the cost of longer timelines and lower yields. Yeast occupies a middle ground — eukaryotic processing with industrial scalability. Our project consultation helps you select the optimal system based on your protein’s characteristics and intended application.
Expression Systems
E. coli Expression
The workhorse system for high-yield recombinant protein production. Best suited for proteins without complex post-translational modifications.
- Advantages: Fast turnaround (2–3 weeks), high yield, low cost, well-characterized
- Typical Yield: 1–100 mg/L culture
- Best For: Cytokines, growth factors, enzymes, small antigens, soluble domains
- Limitations: Limited post-translational modifications, potential inclusion body formation for eukaryotic proteins
Mammalian Expression
HEK293 and CHO cell expression systems for proteins requiring native folding and mammalian post-translational modifications.
- Advantages: Native glycosylation, proper folding, full PTM profile
- Typical Yield: 1–50 mg/L culture
- Best For: Antibodies, membrane proteins, secreted proteins, therapeutic candidates, glycoproteins
- Turnaround: 4–6 weeks
Yeast Expression
Pichia pastoris expression system combining eukaryotic processing with scalable fermentation.
- Advantages: Moderate glycosylation, high-density fermentation, cost-effective scaling
- Typical Yield: 10–500 mg/L culture
- Best For: Secreted enzymes, industrial proteins, antigens requiring some eukaryotic processing
- Turnaround: 3–5 weeks
Service Workflow
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Gene Synthesis & Codon Optimization — Gene synthesis with host-specific codon optimization to maximize expression yield. Synthetic genes are cloned into appropriate expression vectors with affinity tags (His, GST, MBP, FLAG) as needed.
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Expression Screening — Small-scale expression screening to identify optimal conditions: temperature, induction time, and host strain. Solubility assessment for E. coli expression.
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Scale-Up Expression — Optimized conditions scaled to deliver the required protein quantity.
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Purification — Affinity chromatography (Ni-NTA, GST, Protein A/G) followed by size-exclusion chromatography (SEC) or ion-exchange chromatography (IEX) for polishing as required.
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Quality Control & Delivery — SDS-PAGE purity analysis, Western Blot (tag or target-specific), concentration determination (A280 or BCA), and endotoxin testing if specified. Full QC report included.
Quality Control
| Method | Purpose | Specification |
|---|---|---|
| SDS-PAGE | Purity assessment | ≥90% (Coomassie staining) |
| Western Blot | Identity confirmation | Single band at expected MW |
| A280 / BCA | Concentration determination | As specified by customer |
| SEC-HPLC | Aggregation analysis | Optional, available on request |
| Endotoxin (LAL) | Endotoxin quantification | ≤1 EU/mg (on request) |
| Functional Assay | Activity verification | Customer-specific, available on request |
Frequently Asked Questions
Which expression system should I choose?
E. coli is recommended for proteins ≤50 kDa without disulfide bonds or glycosylation requirements. Choose mammalian expression for antibodies, membrane proteins, or proteins requiring native glycosylation. Yeast offers a cost-effective middle ground for secreted enzymes and antigens.
Do you perform codon optimization?
Yes. We optimize the coding sequence for your chosen expression host as a standard step in the workflow. This significantly improves expression yield for heterologous proteins.
What purification tags are available?
His6, GST, MBP, FLAG, Strep, and Fc tags are routinely available. Tag removal by TEV, thrombin, or Factor Xa cleavage is also offered, with removal verified by SDS-PAGE.
Can you express difficult proteins?
We assess feasibility during the consultation phase. Proteins with multiple transmembrane domains, large molecular weight (>150 kDa), or known toxicity to the host may require alternative strategies such as inclusion body refolding (E. coli), membrane protein-specific vectors, or cell-free expression. We will discuss risks and options transparently.
Do you offer custom assay development for functional validation?
Yes. Enzyme activity assays, binding assays (ELISA, SPR), and cell-based functional assays can be developed on request. Specify your functional validation requirements when requesting a quote.
What documentation do I receive?
Every shipment includes a Certificate of Analysis with SDS-PAGE image, concentration data, purification method details, buffer composition, and storage recommendations. Additional characterization data (Western Blot, endotoxin) is included when relevant.