ACell-penetratingPeptideDerivedfromHumanLactoferrinwithConformation-dependentUptakeEfficiencyReceivedforpublication,June23,2009,andinrevisedform,October19,2009Published,JBCPapersinPress,October26,2009,DOI10.1074/jbc.M109.036426FalkDuchardt‡1,2,IvoR.Ruttekolk§1,WouterP.R.Verdurmen§,HuguesLortat-Jacob¶,JochenBu¨rck�,Hansjo¨rgHufnagel‡,RainerFischer‡,MaaikevandenHeuvel**,DennisW.P.M.Lo¨wik**,GeertenW.Vuister‡‡,AnneUlrich�,MicheldeWaard§§3,andRolandBrock‡§4Fromthe‡InterfacultyInstituteforCellBiology,UniversityofTu¨bingen,AufderMorgenstelle15,72076Tu¨bingen,Germany,the§DepartmentofBiochemistry,NijmegenCentreforMolecularLifeSciences,RadboudUniversityNijmegenMedicalCentre,6525GANijmegen,TheNetherlands,the¶InstitutdeBiologieStructurale,UMR5075CEA-CNRS,Universite´JosephFourier,41rueJulesHorowitz,38027GrenobleCedex1,France,the�KarlsruheInstituteofTechnology,ForschungszentrumKarlsruhe,IBG-2,76131Karlsruhe,Germany,theDepartmentsof**Bio-OrganicChemistryand‡‡ProteinBiophysics,InstituteforMoleculesandMaterials,RadboudUniversityNijmegen,Heyendaalseweg135,6525AJNijmegen,TheNetherlands,and§§INSERMU836,Universite´JosephFourier,GrenobleNeuroscienceInstitute,Group3,38027GrenobleCedex1,FranceThemoleculareventsthatcontributetothecellularuptakeofcell-penetratingpeptides(CPP)arestillamatterofintenseresearch.Here,wereportontheidentificationandcharacteriza-tionofa22-aminoacidCPPderivedfromthehumanmilkpro-tein,lactoferrin.Thepeptideexhibitsaconformation-depen-dentuptakeefficiencythatiscorrelatedwithefficientbindingtoheparansulfateandlipid-inducedconformationalchanges.Thepeptidecontainsadisulfidebridgeformedbyterminalcysteineresidues.Atconcentrationsexceeding10�M,thispeptideundergoesthesamerapidentryintothecytoplasmthatwasdescribedpreviouslyforthearginine-richCPPsnona-arginineandTat.Cytoplasmicentrystrictlydependsonthepresenceofthedisulfidebridge.Tobetterunderstandthisconformationdependence,NMRspectroscopywasperformedforthefreepep-tide,andCDmeasurementswereperfo...
