English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Characterization of a quinole-oxidase activity in crude extracts of Thermoplasma acidophilum and isolation of an 18-kDa cytochrome

MPS-Authors
/persons/resource/persons250603

Gärtner,  Peter
Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max Planck Society;

External Resource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Gärtner, P. (1991). Characterization of a quinole-oxidase activity in crude extracts of Thermoplasma acidophilum and isolation of an 18-kDa cytochrome. European Journal of Biochemistry, 200(1), 215-222. doi:10.1111/j.1432-1033.1991.tb21070.x.


Cite as: http://hdl.handle.net/21.11116/0000-0007-6EE6-B
Abstract
A quinol-oxidase activity was detected in crude extracts of the thermoacidophilic archaebacterium Thermoplasma acidophilum. The activity was optimal at pH 5.4 and 50°C. The Km for ubiquinol-10 was 18 microM. The enzyme was inhibited by 2n-heptyl-4-hydroxyquinoline N-oxide with a Ki of 150 nM. Ubiquinols with different side-chain lengths were oxidized at similar rates, whereas menaquinols were converted at 6-12-fold higher rates compared to ubiquinols. Membranes from T. acidophilum contain cytochromes of b, d and a1 types, as shown by optical spectroscopy. CO difference spectroscopy suggests the existence of a cytochrome o. A b-type cytochrome with an apparent molecular mass of 18 kDa was purified in the presence of high detergent concentrations. It readily forms dimers on SDS/PAGE. This cytochrome also contains Cu, as shown by atomic-absorption spectroscopy. Redox titration suggests that the 18-kDa cytochrome may contain 2 heme groups; b558 with a midpoint potential of 75 mV and b562/553 with a midpoint potential of -150 mV.