In the “nature protocols”[Protocol for the quantitative assessment of DNA concentration and damage (fragmentation and nicks)which is Written by Christos D Georgiou, Ioannis Papapostolou & Konstantinos Grintzalis], there is a sentence in describe the prepare of “unsheared DNA stock solution”, like that:
Dissolve without stirring 1 mg of unsheared calf thymus genomic DNA in 4 ml of sterile TE buffer by letting it stand overnight in an ice-cold bath.
All the problems are in the two words in bold: “TE buffer”, TE buffer is the common used buffer in preparing the DNA solution.
TE buffer recipe:
10 mM Tris, bring to pH 7.5 with HCl
1 mM EDTA
In the following process, the DNA solution is used to be the target of DNAse digestion, to prepare the “Totally fragmented DNA standard solution”
But in my own research, there is no any activity of the DNAse is observed. Every step I do is strictly following the process in this protocol.
What is the problem?
At last, I found that if I use TE buffer to Solvent, in the working solution, the concentration of EDTA is about 1mM. At the same time, EDTA is used as DNAse inhibitor to stop this enzyme reaction in this experiment, and the stopping concentration is 5mM. EDTA concentrations in working solution and in stopping solution are In the same order of magnitude.
In order to verify my conjecture, I use double distilled water instead of TE buffer, the activity of DNAse is working correctly
Obviously, this article of “nature protocol” is wrong. From this tiny event, I understand that there is no authority in the field of science, or at least every authority have chance to make mistakes.