Frequently Asked Questions (Q&A)

To help customers select and use our products more efficiently, we have compiled answers to some of the most frequently asked questions. We hope these FAQs make it easier for you to find the information you need.

Q1: Which competent cells, antibiotic resistance, and culture temperature should I use for plasmid DNA in dry-powder form?

A: Enter the plasmid catalog number on our website to view detailed product information, including the recommended competent cells, antibiotic resistance, culture temperature, and complete plasmid sequence.

Q2: How should I handle and use plasmid DNA in dry-powder form?

A: Please refer to our Product Instructions for detailed instructions on how to dissolve and use plasmid DNA in dry-powder form.

Q3: How much plasmid DNA is provided in dry-powder form?

A: We typically provide 0.5–2 μg of plasmid DNA in dry-powder form. The amount is sufficient for transformation, but the exact quantity is not guaranteed.

Please transform the plasmid into competent cells first, then select a single colony, expand the culture, and extract the plasmid DNA before using it for downstream experiments.

Q4: How should I store plasmid DNA after dissolving the dry powder?

A: Dissolved plasmid DNA is generally stored at −20°C. For longer-term storage, −80°C is recommended.

Q5: What concentration of antibiotics should I use?

A: We have compiled recommended concentrations for commonly used research antibiotics. Please refer to our Antibiotic Usage Guide for detailed information.

Q6: A plasmid is recommended for transformation into Stbl3. Can I use DH5α or TOP10 instead?

A: Not recommended.

Some plasmids are prone to recombination or instability in certain host strains. Using DH5α or TOP10 for these plasmids may increase the risk of unwanted recombination during propagation, and some genetic elements may be deleted or rearranged.

Therefore, whenever a specific host strain such as Stbl3 is recommended for a plasmid, it is best to use the recommended strain.

Q7: What are the specifications for lentivirus products?

A:

Titer: 1 × 10^8 TU/mL

Package size: 200 μL × 5 vials

For detailed information on handling and use, please refer to our Lentivirus Product Instructions.

Q8: Can I directly inoculate and culture bacteria from a plasmid glycerol stock?

A: No. We recommend first streaking the glycerol stock onto an appropriate agar plate using the four-quadrant streaking method.

After obtaining well-isolated single colonies, select a single colony for liquid culture.

Q9: Why does the plasmid band appear larger than the expected plasmid size after agarose gel electrophoresis?

A: Purified plasmid DNA can exist in several different conformations, including supercoiled, linear, and open circular forms. These conformations migrate through agarose gels at different rates.

Under typical electrophoresis conditions, the migration speed generally follows:

Supercoiled > Linear > Open circular

Therefore, the apparent position of an uncut plasmid on an agarose gel cannot be directly compared with a linear DNA ladder to determine its actual size.

If you need to accurately evaluate plasmid size, digest the plasmid with an appropriate restriction enzyme to linearize the plasmid before electrophoresis, and then compare its migration with a suitable DNA ladder.

Q10: What concentration and quantities are available for plasmid maxiprep products?

A: For high-copy plasmids, the minimum concentration for our plasmid maxiprep products is 500 ng/μL.

Available quantities include:

• 100 μg

• 200 μg

• 500 μg

• 1 mg

Production and pricing are determined according to your specific requirements.

For low-copy plasmids, the production quantity and pricing need to be evaluated based on the specific plasmid and its copy number.