Protein sorting by high performance liquid chromatography. 2. Separation of isophosphorylates of recombinant human DNase I on a polyethyleneimine column

Anion exchange HPLC with a polyethylenimine (PEI) column separates recombinant human deoxyribonuclease I (rhDNase) glycoforms according to the extent and positions of phosphorylation of mannose residues in N-liked oligosaccharides. The separation provides a selectivity unavailable by anion exchange HPLC with other columns or by isoelectric focusing gel electrophoresis and can be used to quantify the phosphate content of preparations of rhDNase. Tryptic mapping of fractions collected from the column and treated with alkaline phosphatase was used to identify the sites of phosphorylation