Question 1

Which expression systems do you offer (CHO, HEK, E. coli, insect, yeast…)?

Accepted Answer

We offer a full panel of expression platforms to match your protein and application. This includes mammalian systems (CHO and HEK), with our proprietary XtenCHO® Race CHO line delivering top-tier performance for demanding projects. We also provide expression in insect cells, yeast, E. coli, and Bacillus subtilis for secreted proteins or specific production needs.

Question 2

How do I determine which system is best for my protein (size, glycosylation, solubility, function…)?

Accepted Answer

The optimal system depends on your protein’s characteristics and intended use. For example, mammalian systems are preferred when native folding or post-translational modifications are required, while E. coli can be the fastest and most cost-effective option for simpler proteins and short timelines. In all cases, our PhD-level experts will review your target and constraints with you and recommend the most suitable strategy.

Question 3

Can you express challenging proteins such as membrane proteins, secreted proteins, or multi-domain constructs?

Accepted Answer

Yes. We often handle complex targets, including membrane proteins, secreted proteins, and multi-domain constructs. Mammalian expression, especially with XtenCHO Race, is particularly well suited for difficult proteins. With over 1,500+ projects completed, our team has built deep expertise on hard-to-express targets and is recognized as a market reference for complex antibody and protein projects.

Question 4

Do you provide codon optimization or sequence engineering before expression?

Accepted Answer

Yes, we always optimize codons using our proprietary AI-powered tool to maximize expression efficiency. Additionally, we can analyze your sequence to identify any potential liabilities and can propose targeted mutations to improve developability and performance, ensuring your protein is ready for successful production.

Question 5

What scale options are available (small-scale screening, mid-scale, gram-scale)?

Accepted Answer

We support every scale, from high-throughput screening and small-scale expression to mid-scale production and gram-level manufacturing. Depending on your needs, we can run large-scale transient expression in bioreactors or develop stable cell lines for long-term, high-volume production.

Question 6

What purification techniques do you use (affinity, ion exchange, SEC, tag-based…)?

Accepted Answer

We use a range of purification techniques to ensure the highest quality protein. Our routine methods include Nickel (His-tag), Streptactin, antigen-affinity, Protein A/G, Ion Exchange (IEX), and Size Exclusion Chromatography (SEC). It can be tailored based on your protein’s specific needs.

Question 7

Do you offer additional services like tag removal, refolding, or buffer optimization?

Accepted Answer

Yes, we offer a variety of additional services to ensure optimal protein performance. These include tag removal, refolding, buffer optimization, endotoxin removal, stability testing, and concentration up to 50mg/mL, all tailored to meet your project requirements.

Question 8

What QC assays do you provide (SDS-PAGE, SEC-HPLC, endotoxin, concentration, activity tests…)?

Accepted Answer

We perform a comprehensive set of quality control assays, including SDS-PAGE, ELISA, FACS, SPR/BLI, SEC-HPLC, nanoDSF, MS, endotoxin assays, and concentration determination by UV280/Bradford, to ensure your protein meets the highest standards.

Question 9

What are your typical timelines for transient versus stable expression?

Accepted Answer

Transient expression projects can start from 15 business days, depending on the system and complexity. Stable cell line development typically requires around 4.5 months, reflecting the time needed to generate and validate high-performing stable clones.

Question 10

Can I supply my own vector, sequence, or cell line?

Accepted Answer

Yes, you can supply your own vector or sequence, and we can handle the vector construction for you. However, we use our own optimized cell lines for expression to ensure maximum efficiency and consistency.

Question 11

How flexible is your workflow? Can you adapt it to my preferred tags, buffers, and conditions?

Accepted Answer

Our services are highly customizable. We can adapt our workflow to suit your protein’s specific needs, including your preferred tags, buffers, and conditions, ensuring the best possible outcome for your project.

Question 12

Can you ensure endotoxin-free preparations for cell-based or in vivo studies?

Accepted Answer

Yes, we can guarantee endotoxin-free preparations with levels as low as <0.1 EU/mL.

Question 13

What documentation accompanies each batch?

Accepted Answer

Each batch is accompanied by a Certificate of Analysis (CoA), a production report with quality control data, and a packing slip, providing full traceability and transparency for your project.

Question 14

Do you provide scalable solutions from discovery-grade to preclinical-grade protein production?

Accepted Answer

Yes. We can support early discovery programs with high-throughput expression to screen and select candidates, then scale up into larger-volume production under strict process control. For preclinical applications, we also provide enhanced purity, QC, and documentation to meet your functional and regulatory expectations.

Question 15

How do you guarantee purity, stability, and activity of the final protein?

Accepted Answer

While we guarantee yield and purity based on SDS-PAGE and SEC-HPLC after a pilot run, activity for antibodies is also guaranteed based on ELISA results. We ensure the highest quality proteins, optimized for your application, after performing thorough testing and validation.

Question 16

Can I request pilot runs before committing to large-scale production?

Accepted Answer

Yes, we always conduct pilot runs to determine the optimal conditions, yield, and purity before committing to large-scale production.

Question 17

Can you support downstream applications such as assay development, antibody generation, or structural studies?

Accepted Answer

Yes, we can support assay development such as ELISA and antibody generation, leveraging our expertise in hybridoma, phage display, and single B cell technologies. However, we do not conduct structural studies at this time.

Question 18

What post-project support do you offer (storage, re-expression, additional purification steps…)?

Accepted Answer

We offer a wide range of post-project support, including storage, production optimization, scale-ups, purification polishing, sequence optimization (e.g., affinity maturation and developability improvement), and stable cell line development, ensuring your protein can be used long-term and in future applications.

Custom Protein Expression Services