Tris-trihydroxymethylaminomethane is an organic compound with the molecular formula of (hoch2) 3cnh2. Tris is commonly used in the Tae and tbe buffers (for the dissolution of nucleic acids) in biochemical experiments. Its amino group can condense with aldehydes.
Tris is a weak base, and the pH value of Tris alkali aqueous solution is about 10.5. Generally, hydrochloric acid is added to adjust the pH value to the required value to obtain the buffer solution of this pH value. The effective buffer range of the buffer solution is between pH7.0 and 9.2, but the effect of temperature on the pKa of Tris should be noted. At room temperature 25 ℃, PKA is 8.1.
Because Tris buffer is a weak alkaline solution, DNA will be deprotonated in such a solution to improve its solubility. People often add EDTA into Tris hydrochloric acid buffer to make "Te buffer", which is used to stabilize and store DNA. If the acid solution regulating pH value is replaced with acetic acid, then "TAS / acetate / EDTA" is obtained, and "Tris / borate / EDTA" is obtained when the acid solution is replaced with boric acid. These two buffers are usually used in nucleic acid electrophoresis experiments.
Preparation of Tris HCl and Tris EDTA:
1、 1m Tris HCl (pH 7.4, 7.6, 8.0) to prepare 1000ml
Preparation method:
a. Weigh 121.1g Tris into a 1000ml beaker.
b. Add about 800ml deionized water, and fully stir to dissolve.
c. Add concentrated HCl into the following table to adjust the required pH value.
| pH value | Concentrated HCl |
| 7.4 | About 70ml |
| 7.6 | About 60ml |
| 8.0 | About 42ml |
d. Dilute the solution to 1000ml.
e. Store at room temperature after high temperature and high pressure sterilization.
Note: the solution should be cooled to room temperature before setting the pH value, because the pH value of Tris solution varies greatly with the temperature. The pH value of the solution will be reduced by about 0.03 units for every 1 ℃ rise in temperature.
2、 1.5m Tris HCl (pH 8.8) to prepare 1000ml
Preparation method:
a. Weigh 181.7g Tris into a 1000ml beaker.
b. Add about 800ml deionized water, and fully stir to dissolve.
c. Adjust the pH value to 8.8 with concentrated HCl.
d. Dilute the solution to 1000ml.
e. Store at room temperature after high temperature and high pressure sterilization.
Note: the solution should be cooled to room temperature before setting the pH value, because the pH value of Tris solution varies greatly with the temperature. The pH value of the solution will be reduced by about 0.03 units for every 1 ℃ rise in temperature.
3、 TE is Tris EDTA buffer (10mm Tris, 1mm EDTA, pH7.4, ph7.6, ph8.0).
10 × TE buffer (pH 7.4, 7.6, 8.0) 100mm Tris HCl, 10mm EDTA to prepare 1000ml
Preparation method:
a. Measure the following solutions and put them into a 1000ml beaker.
①1M Tris-HCl Buffer(pH7.4，7.6，8.0) 100ml；
②500mM EDTA(pH8.0) 20ml
b. Add about 800ml deionized water into the beaker and mix evenly.
c. After the solution is fixed to 1000ml, it is sterilized under high temperature and pressure.
d. Store at room temperature.
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