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Latest Questions
When analyzing synthetic Oligo DNA products using 3% Agarose gel electrophoresis, many bands are observed, Why?
Denaturing PAGE electrophoresis must be used for Oligo DNA. Oligo DNA is single-stranded and prone to forming complex secondary structures. Therefore, during Agarose gel electrophoresis, multiple bands often appear (and Agarose gel electrophoresis cannot be used for quantification).
After measuring the OD value of the product, if the OD260/OD280 ratio is <1.8, is the product quality (purity) qualified?
Nucleic acids have strong absorption near 260 nm, while proteins absorb strongly near 280 nm. When extracting nucleic acids from biological sources, the OD260/OD280 ratio is commonly used to assess nucleic acid purity (a ratio between 1.8–2.0 is typical). This judgment is based on the assumption that the proportions of A, G, C, T in the sequence are roughly equal. However, this is not the case for synthetic DNA/RNA. The sequences are short (typically 20–30 bases), and the proportions of A, G, C, T bases can vary greatly. Due to the different molar extinction coefficients of the various bases, the OD260/OD280 ratio of synthetic DNA/RNA products differs depending on the base composition. For example, when the sequence has a high content of C and T bases, this ratio can be significantly lower than 1.8. Additionally, the sequence order of the bases also affects this ratio. Therefore, the OD260/OD280 ratio cannot be used to evaluate the purity of synthetic DNA/RNA products.