Fatty acylation enhances cellular localization of dansylated phenylalanines

Two series of fluorescent molecules were synthesized by acylation of dansyl ethylenediamine and phenylalanine dansyl ethylenediamine with one of either acetyl (C2), hexanyl (C6), cyclohexanecarbonyl (C7), myristyl (C14), or palmityl (C16) groups and examined for entry and localization in Chinese Hamster Ovary (CHO) cells in tissue culture. Gross total fluorescence retention and cellular microscopic fluorescence patterns were analyzed. In both series, molecules with myristyl or palmityl groups entered cells. Only in the phenylalanine series did hexyl and cyclohexanecarbonyl modification enable entry. Consistent with a mechanism of passive diffusion, entry of compounds into cells was neither energy dependent nor endocytosis linked. Acylated molecules were observed to localize in cytoplasm and not enter nuclei or associate with lipophilic plasma membranes.