Glycogen can conveniently substitute for tRNA as a carrier for nucleic acid precipitation. Although Molecular Biology grade glycogen can be purchased from a number of vendors, the main disadvantage is that it is very expensive (e.g., About 100 dollars/20-40 mg).
Here we present a simple and inexpensive protocol to prepare a large amount of glycogen which is suitable for any kind of Molecular Biology application (we routinely use it for RNA work).
Procedure
<procedure
Start by dissolving 5 gr. of glycogen (from Oyster, Sigma G 8751) in 10 ml of milli-Q water. Extract once with one volume of Phenol followed by one extraction with one volume of Chlorophorm. Add one volume of absolute ethanol to the supernatant, at this point the glycogen will precipitate instantaneously. Collect the precipitate by centrifugation and air dry completely the pellet. Weigh the powder so obtained and resuspend it in autoclaved milli-Q water at a convenient stock concentration (10-20 mg/ml is suggested). Store in the freezer in 1-mL aliquots.