ENZYME-LINKED IMMUNOSORBENT ASSAYS FOR THE MEASUREMENT OF BLOOD GROUP-A AND GROUP-B GLYCOSYLTRANSFERASE ACTIVITIES

ELISA assays have been developed for alpha(1-3)N-acetygalactosaminyltr ansferase (blood group A transferase) and alpha(1-3)galactosyltransfer ase (blood group B transferase) activities. In these assays, microtitr e plates coated with the bovine serum albumin conjugate of a synthetic Fuc-alpha-2Gal-beta-R acceptor substrate are incubated with the appro priate nucleotide donor (UDP-GalNAc or UDP-Gal) and human serum as the enzyme source. The resulting trisaccharide products Fuc-alpha-1-2(Gal NAc-alpha-1-3)Gal-beta-R-BSA or Fuc-alpha-1-2(Gal-alpha-1-3)Gal-beta-R -BSA are detected and quantified with monoclonal antibodies selected n ot to cross-react with the substrate structure. With less than a micro liter of human serum, product formation is proportional to enzyme conc entration and to time of incubation of up to 90 min.