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HOQNO interaction with cytochrome b in succinate:menaquinone reductase from Bacillus subtilis

Smirnova, Irina A.; Hägerhäll, Cecilia; Konstantinov, Alexander A. and Hederstedt, Lars LU (1995) In FEBS Letters 359(1). p.23-26
Abstract
2-n-Heptyl4-hydroxyquinoline-N-oxide (HOQNO) inhibits the succinate:quinone oxidoreductase activity of isolated and membrane-bound succinate:menaquinone oxidoreductase of B. subtilis. The inhibition pattern resembles closely that observed for α-thenoyltrifluoroacetone and carboxins in the mitochondrial succinate:ubiquinone oxidoreductase: ca. 90% of the activity is highly sensitive to HOQNO (K i ca. 0.2 μM for the isolated enzyme) whereas the rest 10% proves to be resistant to the inhibitor. HOQNO binding is shown to perturb the absorption spectrum of the ferrous di-heme cytochrome b of the B. subtilis succinate:quinone oxidoreductase both in the α and Soret bands. In addition, the inhibitor is shown to bring about a negative shift of E m... (More)
2-n-Heptyl4-hydroxyquinoline-N-oxide (HOQNO) inhibits the succinate:quinone oxidoreductase activity of isolated and membrane-bound succinate:menaquinone oxidoreductase of B. subtilis. The inhibition pattern resembles closely that observed for α-thenoyltrifluoroacetone and carboxins in the mitochondrial succinate:ubiquinone oxidoreductase: ca. 90% of the activity is highly sensitive to HOQNO (K i ca. 0.2 μM for the isolated enzyme) whereas the rest 10% proves to be resistant to the inhibitor. HOQNO binding is shown to perturb the absorption spectrum of the ferrous di-heme cytochrome b of the B. subtilis succinate:quinone oxidoreductase both in the α and Soret bands. In addition, the inhibitor is shown to bring about a negative shift of E m of the low-potential heme b. It is suggested that HOQNO interacts with a menasemiquinone binding site near the low-potential heme and suppresses the MQ.−-to-MQH2 step of the quinone reductase reaction but allows partly for the MQ-to-MQ.− transition to occur; dismutation of MQ. formed in the latter reaction to MQ and MQH2 may account for the 10% of the enzyme activity insensitive to HOQNO. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
FEBS Letters
volume
359
issue
1
pages
23 - 26
publisher
Wiley-Blackwell
external identifiers
  • scopus:0028831032
ISSN
1873-3468
DOI
10.1016/0014-5793(94)01442-4
language
English
LU publication?
yes
id
050f76ab-dad3-4cf3-9290-4e4f50b0cf36
date added to LUP
2017-07-18 10:10:26
date last changed
2017-10-08 05:05:04
@article{050f76ab-dad3-4cf3-9290-4e4f50b0cf36,
  abstract     = {2-n-Heptyl4-hydroxyquinoline-N-oxide (HOQNO) inhibits the succinate:quinone oxidoreductase activity of isolated and membrane-bound succinate:menaquinone oxidoreductase of B. subtilis. The inhibition pattern resembles closely that observed for α-thenoyltrifluoroacetone and carboxins in the mitochondrial succinate:ubiquinone oxidoreductase: ca. 90% of the activity is highly sensitive to HOQNO (K i  ca. 0.2 μM for the isolated enzyme) whereas the rest 10% proves to be resistant to the inhibitor. HOQNO binding is shown to perturb the absorption spectrum of the ferrous di-heme cytochrome b of the B. subtilis succinate:quinone oxidoreductase both in the α and Soret bands. In addition, the inhibitor is shown to bring about a negative shift of E m of the low-potential heme b. It is suggested that HOQNO interacts with a menasemiquinone binding site near the low-potential heme and suppresses the MQ.−-to-MQH2 step of the quinone reductase reaction but allows partly for the MQ-to-MQ.− transition to occur; dismutation of MQ. formed in the latter reaction to MQ and MQH2 may account for the 10% of the enzyme activity insensitive to HOQNO.},
  author       = {Smirnova, Irina A. and Hägerhäll, Cecilia and Konstantinov, Alexander A. and Hederstedt, Lars},
  issn         = {1873-3468},
  language     = {eng},
  number       = {1},
  pages        = {23--26},
  publisher    = {Wiley-Blackwell},
  series       = {FEBS Letters},
  title        = {HOQNO interaction with cytochrome b in succinate:menaquinone reductase from <em>Bacillus subtilis</em>},
  url          = {http://dx.doi.org/10.1016/0014-5793(94)01442-4},
  volume       = {359},
  year         = {1995},
}