The Proteins: Volume II, Part A

Nucleic acids are found in all living cells whether animal or vegetable, and in association with proteins are located in all systems responsible for the multiplication of cell constituents and for protein synthesis. The study of nucleic acids began with the brilliant work of Friedrich Miescher, the Swiss physiologist, who at the age of twenty-five1'2 discovered a phosphorus-containing substance as the main constituent of cell nuclei. The object of his research was to study the chemical composition of cells, and Hoppe-Seyler suggested to him that a good source of uniform cells would be pus. Among the various cell constituents, his main interest was in the composition of the nuclei, and by treating the cells with very dilute hydrochloric acid in the cold and then shaking them vigorously with ether and water,3 he succeeded in isolating free nuclei. These were unaffected by water, but in dilute alkali or in salt solutions they became swollen, and in the alkali a substance was extracted which could be precipitated by acetic acid or by hydrochloric acid. This material gave the biuret and xanthoproteic reactions, but in its general properties did not resemble any protein known at that time.