Ifyourpeptideissynthesizedwithaterminalcysteineresidue(i.e.,afreesulfhydrylgroup,-SH),youcanuseanymaleimide-activatedcarrierproteintocreateanimmunogen.One-stepchemicalreactionsareeasywithPierceSulfo-SMCCPre-ActivatedCarrierProteins(Figure1).Ifyourhaptendoesnothaveasulfhydrylgroup,youcanuseEDCchemistry(Figure2)tocoupleamines(lysine)orcarboxylicacids(glutamic,asparticacidor5"-phosphate)tothecarrierprotein.Keyholelimpethemocyanin(KLH),whichisisolatedfromthegiantseamolluscMegathuracrenulata,isoneofthemostpopularcarrierproteinsusedtocreateanimmunogenforinjection.KLHinducesastrongantibodyresponsebecauseofitslargemass(>106M.W.)andbecauseitisanon-mammalianprotein.PiercerecentlyintroducedmaricultureKLH(mcKLH),aproductthatislessdamagingtomarineaquaticenvironmentsbecausethemolluscsareharvestedandmaintainedinsaltwatertanks.Thecharacteristicblue,opalescentcolorofmcKLHishighlysoluble,makingcouplingreactionseasiertocomplete. Figure1.PeptideCarrierConjugationusingMaleimideActivatedCarriers Figure2.EDC-MediatedPeptide-CarrierConjugation