Monoacylation of ribonuclease A enables its transport across an in vitro model of the blood–brain barrier

Abstract : A major challenge in correcting disorders affecting the central nervous system is to induce blood-brain barrier (BBB) crossing of exogenous biological compounds such as proteins or specific nucleic acid sequences. Fatty acids, due to their high membrane affinity and low toxicity, are good potential candidates to promote this barrier crossing when covalently bound to proteins. In this paper, we report that regiospecific monoacylation of ribonuclease A (RNase A) enables its transport across an in vitro model of the BBB. Myristoylated, palmitoylated and stearoylated RNases A were prepared using reversed micelles as microreactors. All the purified acylated RNases A kept their original enzymatic activity. A single fatty acid moiety was linked to RNase A through the α-amino group of its N-terminal lysine as shown by powerful analytical techniques. The ability of monoacylated RNases A to cross an in vitro model of the BBB is strictly dependent on the acyl chain length, which must be at least 16 carbon atoms long.