Some Observations on the Isolation and Estimation of the Soluble Nucleotides of Wheat Seedlings

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Abstract
Extracts of germinating wheat seedlings contain substances which absorb ultraviolet light strongly but are not nucleotides. In particular, two glucosides seriously interfere with the isolation and estimation of soluble nucleotides and these compounds are not separated from the nucleotides by a charcoal adsorption procedure. A new extraction method is now described which avoids the use of charcoal. Freeze-dried tissue powders placed above a column of cellulose powder are extracted first with methanol/5 per cent, potassium acetate buffer pH 6.0 (90:10), then absolute ethanol, and finally with 30 per cent, ethanol containing acetic acid (0.01 M). The effluent containing the nucleotides is subjected either to dialysis or to ion-exchange resin absorption. During germination soluble nucleotides in the endosperm remain at a low level, but in the embryo there is a thirtyfold increase in 2 days. No evidence for the presence of a cytosine compound in the soluble nucleotide fraction of wheat embryos has been obtained. Guanine, adenine, and uridylic acid were the only detectable products of acid hydrolysis of the wheat seedling soluble nucleotides.