title: Human carboxymethylenebutenolidase as a bioactivating hydrolase of olmesartan medoxomil in liver and intestine.
abstract: Olmesartan medoxomil (OM) is a prodrug type angiotensin II type 1 receptor antagonist widely prescribed as an antihypertensive agent. Herein, we describe the identification and characterization of the OM bioactivating enzyme that hydrolyzes the prodrug and converts to its pharmacologically active metabolite olmesartan in human liver and intestine. The protein was purified from human liver cytosol by successive column chromatography and was identified by mass spectrometry to be a carboxymethylenebutenolidase (CMBL) homolog. Human CMBL, whose endogenous function has still not been reported, is a human homolog of Pseudomonas dienelactone hydrolase involved in the bacterial halocatechol degradation pathway. The ubiquitous expression of human CMBL gene transcript in various tissues was observed. The recombinant human CMBL expressed in mammalian cells was clearly shown to activate OM. By comparing the enzyme kinetics and chemical inhibition properties between the recombinant protein and human tissue preparations, CMBL was demonstrated to be the primary OM bioactivating enzyme in the liver and intestine. The recombinant CMBL also converted other prodrugs having the same ester structure as OM, faropenem medoxomil and lenampicillin, to their active metabolites. CMBL exhibited a unique sensitivity to chemical inhibitors, thus, being distinguishable from other known esterases. Site-directed mutagenesis on the putative active residue Cys(132) of the recombinant CMBL caused a drastic reduction of the OM-hydrolyzing activity. We report for the first time that CMBL serves as a key enzyme in the bioactivation of OM, hydrolyzing the ester bond of the prodrug type xenobiotics.
authors.affiliation: Drug Metabolism and Pharmacokinetics Research Laboratories, Daiichi Sankyo Co. Ltd., Tokyo, Japan. ishizuka.tomoko.xx@daiichisankyo.co.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishizuka
authors.forename: Izumi
authors.initials: I
authors.lastname: Fujimori
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Kato
authors.forename: Chisa
authors.initials: C
authors.lastname: Noji-Sakikawa
authors.forename: Motoko
authors.initials: M
authors.lastname: Saito
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yoshigae
authors.forename: Kazuishi
authors.initials: K
authors.lastname: Kubota
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kurihara
authors.forename: Takashi
authors.initials: T
authors.lastname: Izumi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ikeda
authors.forename: Osamu
authors.initials: O
authors.lastname: Okazaki
mesh_terms: D000595:Amino Acid Sequence; D047228:Angiotensin II Type 1 Receptor Blockers / Q000493:pharmacokinetics; D001711:Biotransformation; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology; D017931:DNA Primers / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D007422:Intestines / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D000068557:Olmesartan Medoxomil; D011247:Pregnancy; D011355:Prodrugs / Q000737:chemistry / Q000493:pharmacokinetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013777:Tetrazoles / Q000737:chemistry / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D017931:DNA Primers; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011355:Prodrugs; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013777:Tetrazoles; D000068557:Olmesartan Medoxomil; D002265:Carboxylic Ester Hydrolases; C046130:carboxymethylenebutenolidase