HYDROXYAPATITE FOR CHROMATOGRAPHY .3. CATION AND PH EFFECTS ON FRACTIONATION OF TRANSFER-RNA FOR CRYSTALLIZATION

Hydroxyapatite (HA) prepared by a new method was applied to the rapid fractionation of R. coli tRNA. Elution of 5° with sodium or potassium phosphate, at two pH values, showed that the order of elution depended on both the buffer cation and the pH. These variations, and that due to temperature, were attributed to changes in tRNA structures which altered the pattern of exposed phosphate charges. The molarity at which tRNA started to elute was lowest at high pH, suggesting that HPO42- was more effective that H2PO4- in displacing from HA. tRNA fractions from a column of benzoylated DEAE-cellulose were fractionated on HA to give nine species of purity 850-1600 pmoles per A260 unit, four of which could be crystallized. © 1978.