AGGREGATES OF AN AMPHIPHILIC SYNTHETIC PEPTIDE BIND AND DELIVER ALL-TRANS RETINOL AND ALL-TRANS-RETINOIC ACID INTO FIBROBLAST CELLS

The structure and conformational behaviour of a vector peptide, design ed by association of a fusion peptide and a nuclear localization seque nce, are described. A beta-sheet domain is observed in which fluoresce nce measurements show that ten peptide molecules bind one all-trans re tinol or all-trans retinoic acid molecule with a strong affinity (K'(d ) = 40 nM). Stoichiometry and affinity of the binding can be compared with those of cellular retinoid binding proteins, the structure of whi ch is an anti-parallel beta barrel. Analogy between the system under s tudy and cellular retinoid-binding proteins is discussed. Peptide-help ed inter nalization and subsequent perinuclear localization of retinol in human fibroblast cells confirm this analogy. Also, this last resul t shows that the peptide is an efficient carrier for insoluble substan ces like retinoids.