Plasmids are DNA molecules other than chromosomes (or mimics) in organisms such as bacteria, yeast and actinomycetes, present in the cytoplasm (except in yeast, where the 2 μm plasmid is present in the nucleus), with the ability to replicate autonomously, allowing them to maintain a constant copy number even in offspring cells and express the genetic information they carry, as closed-loop, double-stranded DNA molecules. Plasmids are not essential for bacterial growth and reproduction and can be lost on their own or eliminated by artificial treatments, such as heat and UV light. The genetic information carried by plasmids can confer certain biological traits to the host bacteria and facilitate their survival under specific environmental conditions.
Large amounts of extracted plasmid DNA generally need to be further purified, and column chromatography and cesium chloride gradient centrifugation methods are commonly used. All of the purification methods often used take advantage of the relatively small size of the plasmid DNA and the covalently closed loop nature of both. For example, the separation of plasmid and chromosomal DNA by cesium chloride-ethidium bromide gradient equilibration centrifugation depends on the amount of ethidium bromide bound to the linear and closed-loop DNA molecules.
Figure 1. The process of plasmids DNA purification.
In terms of years' professional experience in this field, Creative Biogene can provide you with the most affordable and highest quality plasmid DNA purification services.
Creative Biogene has a wide selection of high-performance and cost-effective plasmid purification technologies designed to help you overcome common plasmid preparation problems, such as low recovery and residual impurities.
1) Rapid preparation of molecular experimental grade plasmids
Using silica mold technology, endotoxin >10 EU/μg with a total time of 15-60 min and yields up to 20μg-1mg for PCR, cloning and sequencing.
2) Ultra-pure, high-quality plasmid preparation
Using anion exchange technology, endotoxin 0.1-1 EU/μg, total time 30 min, yield up to 20 μg-15 mg, can be used for cell line transfection and all molecular biology experiments.
3) Improved extraction purity for sensitive analytical applications
Endotoxin-free <0.1 EU/μg with a total time of 90-120 min and yields up to 1.5-15 mg using anion-exchange membrane technology for primary and stem cell transfection, gene therapy and vaccine research, all standard transfection applications and all molecular biology experiments.