How does a DNA binding column work - (May/12/2011 )
Hi,
what is the principle behind a DNA binding column?
How does it bind DNA and why can water dilute the DNA from the column
while wash buffer cannot?
pH is the answer - also 70% ethanol (usually the main component in wash buffer) won't dissolve DNA.
there are two types of columns in use.
cation exchange columns and silicon absorption columns.
The qiagen miniprep column is of the latter type. The qiagen maxiprep column is of the former.
In the cation exchange column, a high salt solution is used to elute the DNA. While in the silicon adsorption column, water is used to elute the DNA.
The exact mechanism how the silicon adsorption columns work is not quite clear. One idea is as follows. Chaotropic agent guandium HCl, which disrupt water structure, allow positively charged ions to form a salt bridge between the negatively charged silica and the negatively charged DNA backbone under high salt conditions,. While this bridge exist (in this high salt environment), the DNA can be washed, removing all other molecules.
This is one idea I have read.
perneseblue on Fri May 13 04:45:02 2011 said:
there are two types of columns in use.
cation exchange columns and silicon absorption columns.
The qiagen miniprep column is of the latter type. The qiagen maxiprep column is of the former.
In the cation exchange column, a high salt solution is used to elute the DNA. While in the silicon adsorption column, water is used to elute the DNA.
The exact mechanism how the silicon adsorption columns work is not quite clear. One idea is as follows. Chaotropic agent guandium HCl, which disrupt water structure, allow positively charged ions to form a salt bridge between the negatively charged silica and the negatively charged DNA backbone under high salt conditions,. While this bridge exist (in this high salt environment), the DNA can be washed, removing all other molecules.
This is one idea I have read.
Thank you for your rough introduction! Now I've got an idea of how it could work at least