The application of electroelution for the preparative analysis and purification of a variety of biological substances has been well documented (l-8). Through the recent development of a simple nonmembraneous adaptor, an electroelution system was described for the rapid isolation of various molecular species of RNA (8). In this communication we have characterized several specific variables which affect the resolution of RNA during electroelution, such as the pump rate, the composition and dimensions of the gel, and the volume of a given concentration of RNA, in addition to the t,emperature during operation and the current input.
Methods
Acrylamide, bisacrylamide, and N,N,AV',W-tetramethylcthylenediamine (TEMED)
were obtained from Eastman Organic Chemicals (Rochester, New York) and agarose powder from Bio-Rad Laboratories ~Richmond, California).
All other chemicals were of reagent grade and the water doubly distilled.
The ultraviolet absorptiometer, fraction collector and Perpex peristalt,ic pump were LKB Produckter (Stockholm, Sweden). The RKD recorder was from Rikadeniki Kogyo Company Ltd. (Tokyo, Japan). The electroelution adaptor was constructed and the system operated as previously described (8).
RNA from baby hamster kidney (BHK) cells was isolated and purified according to Popescu et al. ( 8) and stored in 200 pg quantities under ethanol at -20". Before use, they were drained free of alcohol and dissolved in E buffer (E buffer contains 13.04 nil Tris-acetate, pH 7.5, 0.02 i34 sodium acetate, and 0.001 M disodium EDTA) (9) containing 10% glycerol.