DETERMINATION OF PHOSPHOSERINE IN HUMAN PEPSINOGENS

It has previously been assumed that, in contrast to porcine pepsinogen , the human pepsinogens are not phosphorylated. The present investigat ions show that phosphorylation does contribute to the electrophoretic heterogeneity of the human pepsinogens. A new chromatographic method f or analysis of phosphoamino acid was developed. Quantitative determina tions of phosphoserine were carried out after hydrolysis in 6 mol l(-1 ) HCl (4 h, 110 degrees C). The recovery value of an authentic sample of phosphoserine, treated in parallel with the unknown samples, was us ed for calculations.