Back to Search
Start Over
Studies on the NADH-menaquinone oxidoreductase segment of the respiratory chain in Thermus thermophilus HB-8
- Source :
- Journal of Biological Chemistry. 265:1360-1368
- Publication Year :
- 1990
- Publisher :
- Elsevier BV, 1990.
-
Abstract
- Five distinct low potential iron-sulfur clusters have been identified potentiometrically in the membrane particles from Thermus thermophilus HB-8. Three of these clusters (designated as [N-1H]T, [N-2H]T, and [N-3]T) exhibit the following midpoint redox potentials and g values (Em8.0 = -274 mV, gx,y,z = 1.93, 1.94, 2.02), (Em8.0 = -304 mV, gx,y,z = 1.89, 1.95, 2.04), and (Em8.0 = -289 mV, gx,y,z = 1.80, 1.83, 2.06), respectively. These clusters, one binuclear and two tetranuclear, have been shown to be components of the energy coupled NADH-menaquinone oxidoreductase complex (NADH dh I). They are reducible by NADH in the piericidin A-inhibited aerobic membrane particles as well as in the purified NADH dh I complex. Two additional very low potential iron-sulfur clusters (one binuclear, [N-1L]T, and one tetranuclear, [N-2L]T) were observed in membrane particles. These clusters possess the following physiochemical properties (Em8.0 = -418 mV, gx,y,z = 1.93, 19.5, 2.02) and (Em8.0 = -437 mV, gx,y,z = 1.89, 1.95, 2.04), respectively. No high potential tetranuclear cluster equivalent to the mitochondrial iron-sulfur cluster [N-2]B was found in this bacterial system. In membrane particles isolated from T. thermophilus HB-8 cells, four different semiquinone species have been identified based on their redox midpoint potentials [Em9(Q/QH2) = 40, -100, -160, -300 mV] and sensitivity to the quinone analogue inhibitor, 2-heptyl-4-hydroxy quinoline-N-oxide. Of these semiquinone species the -100 mV component has been suggested to be part of the NADH dehydrogenase. Piericidin A sensitive delta psi formation has been demonstrated to be coupled to the NADH-MQ1 oxidoreductase in membrane vesicles of T. thermophilus HB-8.
- Subjects :
- chemistry.chemical_classification
Oxidoreductase complex
biology
Semiquinone
Stereochemistry
NADH dehydrogenase
Respiratory chain
Cell Biology
Thermus thermophilus
biology.organism_classification
Biochemistry
Electron transport chain
Crystallography
chemistry.chemical_compound
chemistry
Oxidoreductase
biology.protein
Piericidin A
Molecular Biology
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 265
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi...........4984553f745218cef139b10137ae3bc4