The present invention is based, in part, on the discovery that a modified version of Peptide G (Asn Gly Gln Glu Glu Lys Ala Gly Val Val Ser Thr Gly Leu Ile—SEQ ID NO:2) obtained by replacing Asn with Asp to form Peptide G (Asp Gly Gln Glu Glu Lys Ala Gly Val Val Ser Thr Gly Leu Ile—SEQ ID NO: 1) overcomes the long range stabilization problem of the peptide conjugates and, quite surprisingly, also enhances the immune response, particularly the CD4 related (cell mediated) response, of conjugated peptides (L.E.A.P.S. constructs) as previously described.