An assay procedure for inositol pentaphosphate in avian erythrocytes

A method to determine the concentration of inositol pentaphosphate (IP5) in chicken erythrocytes is described. Lysates of washed erythrocytes were treated with trichloroacetic acid to remove protein and were chromatographed on Dowex-1 chloride columns. After eluting the other organic phosphates with .3 N HCl, IP5 was eluted with .5 N HCl and quantitated by phosphorus assay. The mean for 12 chickens was 15.4 +/- 2.71 micromoles/g hemoglobin. The method should be useful for the assay of large numbers of samples.