PT  - JOURNAL ARTICLE
AU  - Y. Qiu
AU  - A. L. Burlingame
AU  - L. Z. Benet
TI  - Mechanisms for Covalent Binding of Benoxaprofen Glucuronide to Human Serum Albumin
DP  - 1998 Mar 01
TA  - Drug Metabolism and Disposition
PG  - 246--256
VI  - 26
IP  - 3
4099  - http://dmd.aspetjournals.org/content/26/3/246.short
4100  - http://dmd.aspetjournals.org/content/26/3/246.full
SO  - Drug Metab Dispos1998 Mar 01; 26
AB  - Tandem MS has been used to establish the structure and specific binding sites of covalent protein adducts formed upon incubation of the acyl glucuronide of the propionic acid nonsteroidal anti-inflammatory drug benoxaprofen with human serum albumin in vitro. Benoxaprofen 1-O-β-glucuronide was enzymatically synthesized in vitro and incubated with human serum albumin both in the presence and in the absence of NaCNBH3. The modified human serum albumins were digested with trypsin and separated by HPLC. The modified peptides were detected using HPLC-electrospray MS (with selected-ion monitoring) and were structurally characterized by tandem MS using matrix-assisted laser desorption ionization in both the post-source decay and high-energy collision-induced dissociation modes. These studies established that benoxaprofen glucuronide forms covalent adducts with protein nucleophiles both by nucleophilic displacement of glucuronic acid at the anomeric center and by condensation of the rearranged acyl glucuronic acid isomers with ε-amino functions of lysine residues after acyl migration of the aglycone from the anomeric center. Lys-159 was identified as the major binding site. Thus, we have established that members of the less reactive propionic acid class of acyl glucuronides, such as the glucuronide of benoxaprofen, are also capable of reacting with protein nucleophiles to form covalent adducts analogous to those of tolmetin glucuronide (tolmetin is an acetic acid nonsteroidal anti-inflammatory drug), via the mechanisms previously reported from this laboratory, and that the specific covalent binding site profile appears to be drug dependent. The American Society for Pharmacology and Experimental Therapeutics