Biosynthesis of bloodgroup I and i antigens. A sensitive and specific assay of UDP-GlcNAc:beta-galactoside beta 1----3-N-acetylglucosaminyltransferase activity in hematopoietic cells by HPLC.

A sensitive HPLC method for the assay of UDP-GlcNAc:beta-galactoside beta 1----3-N-acetylglucosaminyltransferase activity was developed. Using lactose as an acceptor, the formation of the product GlcNAc beta 1----3Gal beta 1----4Glc can be determined without interference by substrates resulting from enzymatic and chemical breakdown of the donor substrate UDP-GlcNAc. The method is very specific since products of other transferase reactions, which potentially may be formed in the incubations in vitro, elute at positions different from that of GlcNAc beta 1----3Gal beta 1----4Glc. By use of this assay method it could be demonstrated that normal and malignant hematopoietic cells and cell-lines, with the exception of erythrocytes and reticulocytes, contain beta 1----3-N-acetylglucosaminyltransferase activity.