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Chemical Compound Review:

HOQNO 2-heptyl-1-hydroxy-quinolin- 4-one

Synonyms: HQNO, SureCN429766, CPD-7975, Pyo II, AG-F-15998, ...

Iverson, T.M. et al., Bera, T. et al., Kang, J. et al., Rinehart, C.A. et al., Dimroth, P. et al., et al.

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Disease relevance of Pyo II

Co-crystallization studies of the E. coli QFR with the known quinol-binding site inhibitors 2-heptyl-4-hydroxyquinoline-N-oxide and 2-[1-(p-chlorophenyl)ethyl] 4,6-dinitrophenol establish that both inhibitors block the binding of MQH(2) at the Q(P) site [1].
The generation of CCCP-resistant membrane potential was inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide that is known to inhibit the Na+-motive NADH oxidase of Vibrio alginolyticus [2].
Membranes of Klebsiella pneumoniae, grown anaerobically on citrate, contain a NADH oxidase activity that is activated specifically by Na+ or Li+ ions and effectively inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) [3].

High impact information on Pyo II

A respiratory inhibitor, 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO), inhibited the Na+-dependent NADH oxidase but had little effect on the NA+-independent activity of mutant membranes [4].
Transmembrane reduction of alpha-lipoic acid was strongly stimulated by anaerobiosis and anaerobic stimulation was inhibited by 2-(n-heptyl)-4-hydroxyquinoline-N-oxide [5].
However, a clear inhibition with complex III inhibitor, 2-(n-heptyl)-4-hydroxyquinoline-N-oxide; modifiers of sulphydryl groups and inhibitors of glycolysis was revealed [5].
The NADH oxidase was highly sensitive to the respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide [6].
3,3',4',5-Tetrachlorosalicylanilide, carbonyl cyanide m-chlorophenylhydrazone, 2-heptyl-4-hydroxyquinoline-N-oxide, and NaCN all inhibited Na+ extrusion from Na+-loaded cells of V. alginolyticus 118 at pH 8 [7].

Anatomical context of Pyo II

1. 2-Heptyl-4-hydroxyquinoline-N-oxide (HpHOQnO) binds to oxidized mitochondria of Saccharomyces cerevisiae with a dissociation constant of 5 x 10(-8) M and with a ratio of 1 mol per mol cytochrome b [8].

Associations of Pyo II with other chemical compounds

Proline transport was strongly inhibited by carbonylcyanide-m-chlorophenylhydrazone (CCCP), a proton permeant that uncouples photophosphorylation, and by 2-heptyl-4-hydroxyquinoline-n-oxide (HQNO), an inhibitor of photosynthetic electron transport [9].
The activities of the NADH:ubiquinone-1 and NADH:menadione oxidoreductase were very resistant to such respiratory chain inhibitors as rotenone, capsaicin, and AgNO(3), whereas these activities were sensitive to 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) [10].

Gene context of Pyo II

Inhibition at a second site was apparent with 2-(n-heptyl)-4-hydroxyquinoline N-oxide, which blocked the reoxidation of cytochrome b563 but had little effect on cytochrome c relaxation [11].
Respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited the activity of the NADH oxidase by about 90% at a concentration of 40 microM [12].
The NADH oxidase activity was completely inhibited by 60 microM 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO), while the NADH:quinone oxidoreductase activity was about 37% inhibited by 60 microM HQNO [13].
The presence of fumarase was evidenced by in vivo 4C-NMR using 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO): the enzyme showed a high reversibility under physiological conditions [14].

References

Crystallographic studies of the Escherichia coli quinol-fumarate reductase with inhibitors bound to the quinol-binding site. Iverson, T.M., Luna-Chavez, C., Croal, L.R., Cecchini, G., Rees, D.C. J. Biol. Chem. (2002) [Pubmed]
Generation of Na+ electrochemical potential by the Na+-motive NADH oxidase and Na+/H+ antiport system of a moderately halophilic Vibrio costicola. Udagawa, T., Unemoto, T., Tokuda, H. J. Biol. Chem. (1986) [Pubmed]
A primary respiratory Na+ pump of an anaerobic bacterium: the Na+-dependent NADH:quinone oxidoreductase of Klebsiella pneumoniae. Dimroth, P., Thomer, A. Arch. Microbiol. (1989) [Pubmed]
Na+ is translocated at NADH:quinone oxidoreductase segment in the respiratory chain of Vibrio alginolyticus. Tokuda, H., Unemoto, T. J. Biol. Chem. (1984) [Pubmed]
Preliminary evidence on existence of transplasma membrane electron transport in Entamoeba histolytica trophozoites: a key mechanism for maintaining optimal redox balance. Bera, T., Nandi, N., Sudhahar, D., Akbar, M.A., Sen, A., Das, P. J. Bioenerg. Biomembr. (2006) [Pubmed]
A novel aerobic respiratory chain-linked NADH oxidase system in Zymomonas mobilis. Kim, Y.J., Song, K.B., Rhee, S.K. J. Bacteriol. (1995) [Pubmed]
Sensitivity of some marine bacteria, a moderate halophile, and Escherichia coli to uncouplers at alkaline pH. MacLeod, R.A., Wisse, G.A., Stejskal, F.L. J. Bacteriol. (1988) [Pubmed]
Binding and inhibitory effect of 2-heptyl-4-hydroxyquinoline-N-oxide in the presence of ubiquinone-3 in Saccharomyces cerevisiae. Burger, G. Eur. J. Biochem. (1980) [Pubmed]
Energy coupling in the active transport of proline and glutamate by the photosynthetic halophile Ectothiorhodospira halophila. Rinehart, C.A., Hubbard, J.S. J. Bacteriol. (1976) [Pubmed]
HQNO-sensitive NADH:Quinone Oxidoreductase of Bacillus cereus KCTC 3674. Kang, J., Kim, Y.J. J. Biochem. Mol. Biol. (2007) [Pubmed]
Flash spectroscopic characterization of photosynthetic electron transport in isolated heterocysts. Houchins, J.P., Hind, G. Arch. Biochem. Biophys. (1983) [Pubmed]
Enzymatic properties of the membrane-bound NADH oxidase system in the aerobic respiratory chain of Bacillus cereus. Kim, M.S., Kim, Y.J. J. Biochem. Mol. Biol. (2004) [Pubmed]
Enzymatic and energetic properties of the aerobic respiratory chain-linked NADH oxidase system in the marine bacterium Pseudomonas nautica. Cho, K.H., Kim, Y.J. Mol. Cells (2000) [Pubmed]
Re-investigation of glucose metabolism in Fibrobacter succinogenes, using NMR spectroscopy and enzymatic assays. Evidence for pentose phosphates phosphoketolase and pyruvate formate lyase activities. Matheron, C., Delort, A.M., Gaudet, G., Forano, E. Biochim. Biophys. Acta (1997) [Pubmed]

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