ABSTRACT
References .......................................................................................................... 58
Peptides, due to their relatively high polarity and hydrogen bridge forming
propensity, are normally unable to cross lipidic membranes.1 Until the 1990s,
therefore, it was generally believed that peptides would also be unable to enter cells,
and thus the complex nature of the plasma membrane was neglected. This belief was
supported by the experience that no compelling evidence for a cellular import of
peptides had been provided until that time. One of the main reasons for this failure
was the inability of the available protocols to unambiguously discriminate between
the minor internalized and the overwhelming surface adsorbed peptide portions.
