title: Inhibition of isolated Mycobacterium tuberculosis fatty acid synthase I by pyrazinamide analogs.
abstract: An analog of pyrazinamide (PZA), 5-chloropyrazinamide (5-Cl-PZA), has previously been shown to inhibit mycobacterial fatty acid synthase I (FASI). FASI has been purified from a recombinant strain of M. smegmatis (M. smegmatis Deltafas1 attB::M. tuberculosis fas1). Following purification, FASI activity and inhibition were assessed spectrophotometrically by monitoring NADPH oxidation. The observed inhibition was both concentration and structure dependent, being affected by both substitution at the 5 position of the pyrazine nucleus and the nature of the ester or N-alkyl group. Under the conditions studied, both 5-Cl-PZA and PZA exhibited concentration and substrate dependence consistent with competitive inhibition of FASI with K(i)s of 55 to 59 microM and 2,567 to 2,627 microM, respectively. The results were validated utilizing a radiolabeled fatty acid synthesis assay. This assay showed that FASI was inhibited by PZA and pyrazinoic acid as well as by a series of PZA analogs.
authors.affiliation: Department of Chemistry, University at Albany-SUNY, Albany, NY 12222, USA.
authors.forename: Silvana C
authors.initials: SC
authors.lastname: Ngo
authors.forename: Oren
authors.initials: O
authors.lastname: Zimhony
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Chung
authors.forename: Halimah
authors.initials: H
authors.lastname: Sayahi
authors.forename: William R
authors.initials: WR
authors.lastname: Jacobs
authors.forename: John T
authors.initials: JT
authors.lastname: Welch
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D002474:Cell-Free System; D064429:Fatty Acid Synthases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D013058:Mass Spectrometry; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D011718:Pyrazinamide / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D015203:Reproducibility of Results; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D011718:Pyrazinamide; D009249:NADP; D064429:Fatty Acid Synthases; C413881:fatty acid synthase I, mycobacteria