Analysis of the antigen recognition sites of anti-methamphetamine monoclonal antibodies (II): unique feature of MA-3 antibody. 
A monoclonal antibody against methamphetamine (MA-3 mAb) was found to be strongly bound to ephedrine.  This feature was quite different from that of other fourteen mAbs against MA.  Analyses of cDNA sequence and steric conformation by molecular modeling revealed that one hydrophilic pocket was generated in the heavy chain of MA-3 mAb involving CDRH-1 and CDRH-2.  Asn33, Asn35, Asn50 and Asp52 were the main components of the unique pocket capable of binding to the hydroxyl group of ephedrine.