Is the plasmid extraction kit the same as the nucleic acid extraction kit ? What is the difference ? We give an answer through analysis

　　1. After adding absolute ethanol to the wash buffer, the final concentration is almost 70% ethanol solution. In the precipitated DNA, due to the presence of too many salt impurities, which will affect the DNA digestion and other reactions, the wash buffer is to wash away these salt impurities.

　　2. Precipitate DNA with absolute ethanol, which is a commonly used method for DNA precipitation in experiments. The advantage of ethanol is that it can be miscible with water in any ratio. Ethanol and nucleic acid will not have any chemical reaction, so it is very safe for DNA. Ideal precipitant. DNA solution is the stable existence of DNA in a hydrated state. When ethanol is added, ethanol will take away the water molecules around the DNA, making the DNA dehydrated and easy to polymerize. In general experiments, add 2 times the volume of anhydrous Ethanol is mixed with DNA, and the final content of ethanol accounts for about 67%. Therefore, 95% ethanol can also be used instead of anhydrous ethanol (because the price of anhydrous ethanol is much more expensive than 95% ethanol). However, adding 95% ethanol Ethanol increases the total volume, and the DNA dissolves to a certain extent in the solution, so the loss of DNA also increases, especially when multiple ethanol precipitations are used, which will affect the yield. Use 95% ethanol instead of anhydrous ethanol, and use anhydrous ethanol for the final precipitation step. You can also use 0.6 times the volume of isopropanol to selectively precipitate DNA. Generally, it can be placed at room temperature for 15-30 minutes. If you do not add Nucleic acids cannot be precipitated in absolute ethanol and are discarded with the washing solution.

　　3. Sodium dodecylsulfate (sodium dodecylsulfate) becomes potassium dodecylsulfate (PDS) after encountering potassium ions, and potassium ions replace the sodium ions in SDS to form insoluble PDS, while high The concentration of salt makes the precipitation more complete. Everyone knows that SDS likes to combine with proteins. On average, two amino acids are combined with one SDS molecule. The large amount of precipitation generated by potassium and sodium ion replacement naturally precipitates most of the protein, which makes people happy. What's more, the genomic DNA of E. coli was also co-precipitated. This process is not difficult to imagine, because the genomic DNA is too long, and the long DNA is naturally easy to be co-precipitated by PDS, although SDS does not bind to DNA molecules. Need In particular, acetic acid is added to neutralize NaOH, because long-term alkaline conditions will interrupt DNA, so it must be neutralized. Once genomic DNA is broken, as long as it is a 50-100 kb fragment, there will be no The method is then co-precipitated by PDS. Therefore, the alkali treatment time should be short, and it should not be shaken violently, otherwise a large amount of genomic DNA will always be mixed in the final plasmid.

　　Hebei Sanshi Biotechnology Co., Ltd. was established in 2018. It is a high-tech biological enterprise focusing on the development and production of nucleic acid diagnostic raw materials and molecular tool enzymes. It is committed to providing high-quality products and services for the fields of life science and biomedicine. At present, the products cover basic biological reagents related to life science research, as well as core enzyme preparation products and molecular diagnostic testing kits related to food safety, animal diseases, precision medicine and other fields. Sanshi Bio continues to innovate in line with the development trend of the industry era, create value for partners, and make unremitting efforts to establish a national brand.