Consistent quality and performance
QIAGEN Plasmid Plus technology delivers the same performance and quality as anion-exchange technology. The unique binding chemistry of the QIAGEN Plasmid Plus columns ensures that pure plasmid DNA is obtained every time. High-yield protocols and extra buffer volumes are provided with the QIAGEN Plasmid Plus Kits. Yields of up to 10 mg (giga),
2 mg (mega), 1 mg (maxi), and 250 μg (midi) of highly pure plasmid DNA, free of contaminants such as RNA, proteins, and genomic DNA are achieved (see figures "High yields are ensured with QIAGEN Plasmid Plus Kits (QPP)" and "Analytical chromatogram").
Transfection-grade plasmid DNA with very low endotoxin levels
Endotoxins, also known as lipopolysaccharides or LPS, are cell-membrane components of Gram-negative bacteria such as E. coli and are released during the lysis step of plasmid purification. Endotoxins can induce nonspecific activation of immune responses, and thus represent a noncontrollable variable in transfection experiment setup, influencing the outcome and reproducibility of results and making them difficult to compare and interpret.
The endotoxin wash buffer provided in the kits reduces bacterial endotoxins to levels usually below 1 EU/μg DNA. (Endotoxin levels can vary depending on the host strain, culture media, and cell density. If the cell density is very high, endotoxin levels may be slightly higher, ranging from 1–3 EU/μg DNA.) This makes the plasmid DNA suitable for a multitude of applications, including transfection into sensitive cell lines (see figures "Endotoxin levels using QIAGEN Plasmid Plus Kits", "Endotoxin levels using different isolation methods", and "Efficient transfection in sensitive cell lines").