To probe the effect of charge and ligand polar head, we report on the interaction between a plant lipid transfer protein (LTP1) and cationic surfactants, anionic and nonionic polymer grafted lipids, cetyl trimethylammonium. bromide (CTAB), dihexadecyl dimethylammonium bromide (DHDAB), dimyristoyl phosphatidylethanolamine poly(ethylene glycol) (DMPE-PEG2000), and a telechelic polymer (PEG-dioleate), respectively. As revealed by intrinsic protein fluorescence, these ligands were loaded in the protein hydrophobic cavity with an affinity of about 2 muM except for the telechelic polymer for which the affinity was 10 times lower. These results suggest that the protein can bind ligands whatever the nature, size, and charge of their polar head. Moreover, the protein is shown to bind monomers in solution in the case of CTAB since the titration experiment was performed at a concentration lower than its critical micelle concentration (cmc). Altogether, this reveals that the protein does not require any interface to wrap on prior to loading a ligand in its cavity and that the hydrophobic contribution is detrimental. Regarding the stoichiometry, it could be concluded that 2 molecules of each ligand were bound in the protein cavity. This suggests that, in combination with telechelic or hydrophobically modified polymers, the protein could form new assemblies of macromolecules. Two models are proposed to depict how DMPE-PEG2000 can be loaded in the protein cavity, and this is further corroborated by molecular modeling.