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| Titel: |
ADP- and oligomycin-sensitive redox behavior of F_0 b thiol in ATPsynthase depends on neighbored primary structure: Investigations using 14-C-labeled alpha lipoic acid |
| Auteur: |
Fritz Dünschede Klaus Zwicker Hanns Ackermann Guido Zimmer |
| Verschenen in: |
BioFactors |
| Paginering: | Jaargang 19 (2004) nr. 1-2 pagina's 19-32 |
| Jaar: |
2004-02-02 |
| Inhoud: |
Purified ATPsynthase of bovine heart mitochondria has been analyzed for its mobility and reactivity of oligomycin-sensitive sulfhydryl regions in presence of the substrate ADP and oligomycin. Labeling of thiol groups at the hydrophobic F_0 region of the ATPsynthase was increased in the enzyme initially treated with SDS, N-ethylmaleimide and dithiothreitol (modified enzyme). After dialysis or gel permeation the ATPsynthase was treated with [^{14}C] alpha lipoic acid at a molar ratio of 35-85/1 (lipoic acid/ATPsynthase) corresponding to 4-8.6 nmol/mg protein. Under these conditions, ATPase activity of the native enzyme was significantly decreased. After preincubation with ADP, PAGE of the native, [^{14}C] labeled enzyme revealed an increase of radioactivity at a region of 25 kDa deduced to Cys 197 of subunit b. In the modified enzyme the increase in radioactivity was found at 10 kDa. In this context, the sequence Lys-Cys-Ile around Cys 197 of subunit b suggests excessive reactivity of this thiol, as well as ready reversibility by -SH-S-S- interchange. Therefore, previously observed reaction by thiol reagents and antioxidants from outside the mitochondrion can be interpreted with Cys 197 of F_0 b. It accounts for sulfhydryl unmasked by binding of ADP at F1. |
| Uitgever: |
IOS Press |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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