Esben Kirk

Nature of Nitrogenous Constituents in Petroleum Ether Extract of Plasma

Neither the amino nor the non-amino nitrogen obtained in the petroleum ether extract of plasma by the technique of Kirk, Page, and Van Slyke 1 derives entirely from phosphatides. The N:P ratio for lecithin and cephalin is 1, while the Amino N:P ratios are 0 and 1 respectively. In a mixture of these phosphatides the N:P ratio would accordingly be 1, and the Amino N:P ratio between 0 and 1, according to the proportion of cephalin present. Petroleum ether extracts from 10 normal plasmas were prepared and analyzed according to the method of Kirk, Page, and Van Slyke. The N:P ratios varied from 1.7 to 5.5, and averaged 3.4. The Amino N:P ratios varied from 0.6 to 1.7, and averaged 1.7. There was accordingly more of both total N and amino N present in the extract than could be combined in these phosphatides. In extracts from plasma of uremic patients the excess of N and NH2 was still greater. The N:P ratio in 8 cases varied from 3 to 18, and averaged 9, while the Amino N:P ratio ranged from 0.9 to 4.7 and averaged 2.5. Part of both the amino and the non-amino nitrogen is removable from the petroleum ether by shaking with acidified water. The nature of the material is being studied further.