Acid-soluble deoxynucleotides and DNA synthesis in growing yeast after x-irradiation. I. Diphenylamine positive material in synchronized and asynchronously growing cells.

Unauthenticated Download Date | 7/6/17 3:54 AM ACID-SOLUBLE DEOXYNUCLEOTIDES AND DNA SYNTHESIS 1 2 6 7 Estimation of acid-soluble diphenylamine positive compounds 3.0 ml cell extract were heated with 6.0 ml diphenylamine reagent11 in a boiling water bath (10 min.). The samples were cooled in an ice bath (5 min.), and O.D. was measured at 600 nm (4 cm cells). The data were calculated for nmoles "deoxyribosides" per 200 ml culture from a deoxyribose standard. The color intensity (O.D.) was proportional to the number of cells extracted, in the range between at least 0.5 x 109 and 5.0 x 109 cells. Preliminary experiments10, including behaviour against activated charcoal (prepared according to 12) , adsorbability and elution pattern with the anion exchange resin Dowex 1 x 10 (formate form, cf. 14) , and with Sephadex G-15, resp., and susceptibility to hot dilute acid, gave evidence, that more than 90% of the acid-soluble yeast constituents showing a diphenylamine reaction under the above test conditions are deoxyribonucleotides. From standard solutions of numerous substances only deoxyribose and purine deoxynucleotides exhibited a remarkable colour 10.