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 investigations show that phosphorylation does contribute to the electrophoretic heterogeneity of the human pepsinogens. A new chromatographic method for analysis of phosphoamino acid was developed. Quantitative determinations 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 used for calculations.