BINDING-SPECIFICITY OF A MONOCLONAL-ANTIBODY TO HUMAN HB-A

HemoCard(TM) kits use monoclonal antibody-conjugated metal sol particl es in an immuno-concentration assay. The HemoCard Hbs S, C, and E kits detect the three most common hemoglobin variants in both adult and ne wborn samples. The HemoCard Hb A kit can be used in conjunction with H emoCard Hbs S and C (but not HemoCard Hb E) to distinguish heterozygot es from homozygotes. We examined the antigen-binding domain of a monoc lonal antibody to Hb A by testing samples from human and animal source s. We confirmed that the Hb A conjugate recognizes an epitope in which glutamic acid at beta 6 is necessary to provide the proper conformati on for binding. This binding is not affected by substitutions at posit ions directly adjacent to beta 6. However, extensive substitutions in the primary sequence (e.g. in chicken, beta 6: glutamic acid, substitu tions at beta 3, beta 5, beta 9, beta 10, beta 11) may produce conform ational changes, resulting in diminished binding.