Carbonic anhydrase inhibitors. The mitochondrial isozyme VB as a new target for sulfonamide and sulfamate inhibitors.
A lately discovered carbonic anhydrase (hCA, EC 4.2.1.1), the mitochondrial hCA VB, was cloned, expressed, and purified. Kinetic parameters proved it to be 3.37 times more effective than hCA VA as a catalyst for the physiological reaction, with kcat = 9.5 x 10(5) s(-1) and kcat/K(M) = 9.8 x 10(7) M(-1) s(-1), being second only to hCA II among the 16 isoforms presently known in humans. We investigated the inhibition of hCA VB with a library of sulfonamides/sulfamates, some of which are clinically used compounds. Benzenesulfonamides were ineffective inhibitors, whereas derivatives bearing 4-amino, 4-hydrazino, 4-methyl, 4-carboxy moieties or halogenated sulfanilamides were more effective (Ki's of 1.56-4.3 microM). Among the 10 clinically used compounds, acetazolamide, benzolamide, topiramate, and indisulam showed effective inhibitory activity (Ki's of 18-62 nM). Three compounds showed better activity against hCA VB over hCA II, among which were sulpiride and ethoxzolamide, which were 2 times more effective inhibitors of the mitochondrial over the cytosolic isozyme. hCA VB is a druggable target and some of its inhibitors may lead to the development of novel antiobesity therapies.
Nishimori
Isao
I
Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan.
Vullo
Daniela
D
Innocenti
Alessio
A
Scozzafava
Andrea
A
Mastrolorenzo
Antonio
A
Supuran
Claudiu T
CT
D000595:Amino Acid Sequence; D002257:Carbonic Anhydrase Inhibitors / Q000737:chemistry*; D024404:Carbonic Anhydrase V / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D002384:Catalysis; D003001:Cloning, Molecular; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship; D013449:Sulfonamides / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry*
D002257:Carbonic Anhydrase Inhibitors; D007527:Isoenzymes; D013449:Sulfonamides; D013451:Sulfonic Acids; C005741:sulfamic acid; D024404:Carbonic Anhydrase V