A New Type of Phosphoric Acid Compound Iso- Lated from Blood, with Some Remarks on the Effect of Substitution on the Rotation of Z-glyceric Acid.*

The phosphoric acid compounds of the blood may be divided into three groups: protein, lipoid, and acid-soluble (1, 2, 3, 4). In the last are included those compounds that are not precipitated with the proteins and lipoids when the blood is treated with the usual acid protein precipitants. In plasma, this acid-soluble phosphorus seems to consist almost entirely of inorganic phosphate (3, 4, 5, 6, 7). In fact, it is quite possible that the observed differences between the values obtained for total phosphorus and for inorganic phosphate may be due entirely to errors in the methods employed. But in whole blood, as was first shown by Bloor (3) and confirmed by many others (4, 7, 8, 9, lo), this is almost certainly not the case. The differences between the values obtained for inorganic phosphate and for total phosphorus in the proteinand lipoid-free filtrates are too large to make such a hypothesis acceptable without further evidence. In 1921, Zucker and Gutman (11) submitted the trichloroacetic acid filtrates from blood to hydrolysis with acids and found that, whereas some of the organically bound phosphoric acid was readily split off, the remainder was not liberated even after prolonged boiling with acids. This they interpreted as evidence of the presence of at least two organic compounds of phosphorus, one of which they termed “non-hydrolyzable.”