FINE-STRUCTURE EPITOPE MAPPING OF ANTIERYTHROPOIETIN MONOCLONAL-ANTIBODIES REVEALS A MODEL OF RECOMBINANT-HUMAN-ERYTHROPOIETIN STRUCTURE

We have isolated and mapped the rHuEPO epitopes for three noncompeting anti-EPO monoclonal antibodies (MoAbs). The MoAb 9G8A recognizes a li near epitope that includes amino acids 13, 16, and 17. MoAb F12 recogn izes a conformational epitope that includes amino acids 31 through 33, 86 through 91, and 138. MoAb D11 recognizes a conformational epitope that includes amino acids 64 through 78 and 99 through 110. MoAb D11 n eutralizes rHuEPO activity which suggests that its epitope may contain the receptor binding domain. Analysis of the effect of mutations on f olding allowed the identification of buried residues, alpha-helical, a nd non alpha-helical regions. This data along with epitope mapping dat a of anti rHuEPO monoclonals was used to model rHuEPO protein structur e. A model consistent with the data is a 4-helix bundle with short and long interconnecting loops. (C) 1996 by The American Society of Hemat ology.