The binding of bongkrekate to mitochondria
| Autor: | Heinrich Aquila, Wilfried Babel, Maria Appel, Martin Klingenberg |
|---|---|
| Rok vydání: | 1983 |
| Předmět: |
Atractylate
Binding Sites Chemistry Intracellular Membranes Mitochondrion Atractyloside Hydrogen-Ion Concentration Biochemistry Binding Competitive Anti-Bacterial Agents Mitochondria Adenosine Diphosphate Crystallography Membrane Adenosine Triphosphate Molar ratio Single site Biophysics ADP binding Inner mitochondrial membrane Bongkrekic Acid Bongkrekate |
| Zdroj: | European journal of biochemistry. 131(3) |
| ISSN: | 0014-2956 |
| Popis: | The binding of bongkrekate to mitochondrial membrane was investigated using [3H]bongkrekate. These measurements were designed to examine the previously derived reorienting site mechanism which implies that bongkrekate binds to the single carrier site only from the inner face of the mitochondrial membrane. The binding studies confirm pH-dependent accumulation of [3H]bongkrekate inside the mitochondria which superimposes on to binding of carrier sites. By breaking the membrane with Lubrol or sonication, binding to the carrier sites can be titrated and Kd approximately equal to 5 X 10(-8) M is determined. ADP or ATP increases the amount of binding but does not change the Kd. Reciprocally bongkrekate increases ADP binding in those sections of a titration curve where bongkrekate binding is increased by ADP. [35S]Atractylate is displaced by [3H]bongkrekate at a 1:1 molar ratio. This displacement is dependent on ADP concentration with the Km = 0.5 X 10(-6) M. The earlier described isomer, isobongkrekate, also binds specifically to the carrier sites. From competition with bongkrekate a ratio KisoBKAd/KBKAd = 0.10 is determined. [35S]Carboxyatractylate displaces most of [3H]isobongkrekate but only little of [3H]bongkrekate. The rate of displacement is more than 10-times faster for isobongkrekate than for bongkrekate. The displacement is dependent on ADP with a Km = 5 X 10(-6) M. All these results are fully consistent with the single site reorienting mechanism. In no instant do bongkrekate and atractylate as well as ADP or ATP bind simultaneously to the carrier. |
| Databáze: | OpenAIRE |
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