Water-soluble fatty acid derivatives as acylating agents for reversible lipidization of polypeptides

A novel method allowing the conjugation of a fatty acid to a peptide or protein in aqueous buffer is described in this paper. L-Cysteinyl 2-pyridyl disulfide (CPD) (III), which was obtained by reacting L-cysteine (I) with 2,2-dithiopyridine (II), was reacted with the N-hydroxysuccinimide ester of palmitic acid (IV) to yield a water-soluble derivative of palmitic acid, termed Pal-CPD (V). Pal-CPD (V) could be reacted with a sulfhydryl-containing peptide or protein in aqueous buffer to yield the palmitic acid-derivatized conjugate (VI). The palmitic acid-derivatized Bowman-Birk protease inhibitor (BBI), synthesized using this conjugation method, was demonstrated to have 140-fold higher uptake into Caco-2 cell monolayers compared to native-BBI. The biological activity of the conjugate, as assessed using an in vitro transformation assay, was retained.