Abstract
We have previously reported 1 that certain proteins, amino acids, dipeptides, and diketopiperazine are acidic in liquid ammonia, and that they react with metallic sodium to liberate hydrogen with the formation of the corresponding ammono salt. We have also studied the action of sodium upon peptones under similar conditions. The following peptones were used: Armour's Meat Peptone, Merck's Meat Peptone, Witte's Peptone, and silk peptones prepared by treating silk fibroin with 70% sulfuric acid at room temperature for one, 2, 3, 4, and 10 days. We were interested in comparing the properties of peptones in liquid ammonia with the properties of proteins, amino acids, dipeptides, and diketopiperazines, and in comparing the properties of the various peptones with each other.
The procedure was essentially the same as described previously. Peptones are somewhat soluble or are dispersed in liquid ammonia. The solubility of silk peptones varies with the extent of digestion, passing through a maximum on the third day.
In general, we have found that the peptones, Armour's, Merck's, Witte's, and 2 and 3 day silk peptones behave more like diketo-piperazine than like proteins, amino acids, or peptides. When the quantity of hydrogen liberated by a definite amount of dried peptone is plotted against the amount of sodium that is brought into reaction, the curves for these peptones resemble closely the curve for diketopiperazine. With small amounts of sodium, relatively smaller quantities of hydrogen are liberated and greater proportion of the hydrogen is taken up by the peptone. With increasing amounts of sodium, there is a relative increase in the quantity of hydrogen liberated. The maximum is reached when the proportions of 4 gm. atoms of nitrogen are treated with 7.3 gm. atoms of sodium with the liberation of 1.2 gm. atoms of hydrogen.
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