Conversion of proteins to diazeniumdiolate-based nitric oxide donors

Michael reaction of the methoxymethyl-protected monodiazeniumdiolate of pip erazine (MOMPIPERAZI/NO) with 3-maleimidobutyric acid followed by its conve rsion to the N-hydroxy-succinimido ester produces a reagent capable of tran sferring the nitric oxide (NO)-donating diazeniumdiolate group to the termi nal amines of the lysine residues contained in proteins. The reagent has be en used to produce diazeniumdiolated bovine serum albumin (D-BSA) and diaze niumdiolated human serum albumin (D-HSA) containing 22 and 19 modified lysy l groups, respectively. Upon dissolution in pH 7.4 phosphate buffer at 37 d egrees C, these albumin derivatives gradually released all of their contain ed NO (approximately 40 mol/mol of protein) with initial rates of about 30- 40 pmol/min/mg and half-lives on the order of 3 weeks. This methodology is now available for use in exploiting the unique specific metabolic interacti ons of proteins to target NO therapy to specific physiological processes in vivo.