The isolation of highly polymerized desoxypentosenucleic acid from yeast cells.

The nucleic acids occurring in nature are, by convention, divided into two groups, the desoxypentose and the pentosenucleic acids, whose designation emphasizes a difference in their sugar constituents. The extent, however, to which this classification denotes an actual dichotomy rather than a convenient process for the description of a large number of different chemical entities is still subject to conjecture. It appears a matter of real importance to determine whether nucleic acids in general agree with the patterns developed in greater detail for the desoxyribonucleic acid of calf thymus and the ribonucleic acid of yeast. A comparative chemical study of the two nucleic acids isolated from the same cellular material would, in this connection, seem to be one of the most attractive problems. Among the various microorganisms which can be considered as the starting material for the preparation of desoxypentosenucleic acids, yeast is for several reasons one of the most interesting. As yeast ribonucleic acid has been studied extensively, this would offer an opportunity to compare the two acids from the same source. Moreover, since yeast is one of the most widely explored organisms with respect to its metabolic activities, the general problem of nucleic acid metabolism could be approached, once methods for the isolation from yeast of both types of nucleic acid are made available. Finally, yeast is easily obtained in large quantity. The presence in yeast cells of definite chromosome-like elements demonstrable by the nucleal stain of Feulgen has been known for some time (l-6). There seems, however, to be only one report in the literature (7) on the preparation from yeast, with the use of strong alkali, of a nucleic acid said to be similar to thymonucleic acid. The evidence is difficult to appraise, since the substance, characterized by a qualitative desoxypentose test and presumably degraded because of the method of isolation,