title: Activated sulfonamides are cleaved by glutathione-S-transferases.
abstract: In preclinical pharmacokinetic studies and in in vitro rat, dog, and human primary hepatocyte incubations, the sulfonamide (-NH-SO(2)-) bond of a potent inhibitor of the HIV-1 protease containing the p-cyanopyridinyl moiety (PNU-109112), undergoes metabolic cleavage to form the corresponding amine metabolite (PNU-143070). Strikingly, a compound, PNU-140690, obtained by substituting the cyanopyridinyl group of PNU-109112 with a trifluoropyridinyl moiety, was stable under the same in vivo and in vitro conditions used for PNU-109112. The apparent "sulfonamidase activity" present in liver was localized to the cytosolic fraction and shown to be an enzyme-mediated reaction requiring reduced glutathione (GSH). The enzyme responsible was purified in a single step on a GSH immobilized gel and was identified as glutathione-S-transferase (GST) by sequence analysis of peptides obtained by tryptic digestion of the purified protein. Moreover, a mixture of GST isoenzymes purified from rat liver, and three recombinant human GST isoforms, A1-1, M1-1, and P1-1, were active toward PNU-109112 sulfonamide cleavage; the three isoforms exhibited differential rates of PNU-109112 cleavage, demonstrating isoenzyme selectivity.
authors.affiliation: Protein Science, Pharmacia & Upjohn, Incorporated, Kalamazoo, Michigan, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Koeplinger
authors.forename: Z
authors.initials: Z
authors.lastname: Zhao
authors.forename: T
authors.initials: T
authors.lastname: Peterson
authors.forename: J W
authors.initials: JW
authors.lastname: Leone
authors.forename: F S
authors.initials: FS
authors.lastname: Schwende
authors.forename: R L
authors.initials: RL
authors.lastname: Heinrikson
authors.forename: A G
authors.initials: AG
authors.lastname: Tomasselli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001711:Biotransformation; D002460:Cell Line; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D004232:Diuretics / Q000378:metabolism*; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship; D013347:Subcellular Fractions / Q000378:metabolism; D013449:Sulfonamides / Q000378:metabolism*
chemical_list: D004232:Diuretics; D007527:Isoenzymes; D013449:Sulfonamides; D005982:Glutathione Transferase