HEPES
HEPES is a zwitterionic Good's buffer, effective in the pH range of 6.8 to 8.2. This makes HEPES an effective buffer at physiological pH. The buffer can be used in the cell culture medium of a variety of organisms. It can also be used as a binding buffer in protein research, in cation exchange elution experiments, and as a running buffer in gel electrophoresis.
The preparation steps of HEPES:
To prepare 1 liter of 1M HEPES buffer solution, please dissolve 238.30 g HEPES in 750 mL water. Use 10N sodium hydroxide to adjust to the desired pH.
Precautions:
HEPES is soluble in water, inexpensive, and generally biologically inert. However, it does participate in the redox reaction that generates free radicals and interferes with the reaction between DNA and restriction enzymes, but due to steric hindrance, its interference is less than Tris. It is also important to note that when using heterogeneous connexin channels, HEPES should not be used because it will inhibit its function.
PIPES
PIPES is a member of the piperazine buffer family and belongs to the same family as HEPES. It is a zwitterionic Good's buffer, effective in the pH range of 6.1 to 7.5. Since the pH range is slightly different from HEPES, the concentration of PIPES is only half of the concentration of HEPES. The buffer does not complex with metals, so it can be used in solutions containing metal ions.
PIPES preparation steps:
To prepare 1 liter of 1M PIPES free acid buffer solution, add 302.37g PIPES free acid to 600 mL of water. Use 10N sodium hydroxide to adjust to the desired pH.
Precautions:
Until the pH of the solution rises above 6.5, the free acid of PIPES is easily dissolved, but the sodium salt of PIPES is easily dissolved. If you are using a buffer in the free acid form, use sodium hydroxide to convert it to a sodium salt to improve solubility at lower pH. Like HEPES, PIPES is not suitable for experiments involving redox reactions because it causes the formation of free radicals.