Divalent cation dependent ATPase activities of red blood cell membranes: Influence of the oxidation of membrane thiol groups close to each other
✍ Scribed by Scutari, G. ;Ballestrin, G. ;Covaz, A. L.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1980
- Tongue
- English
- Weight
- 594 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0091-7419
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✦ Synopsis
Abstract
An Mg^2+^‐dependent low ATPase activity can be detected in erythrocyte “white membranes,” in addition to that of the well known (Ca^2+^ + Mg^2+^)‐ATPase. The thiol oxidizing agent diamide affects both activities. The oxidation of neighboring thiols seems to leave the mechanism of the (Ca^2+^ + Mg^2+^)‐ATPase amplification system evoked by Ca^2+^ largely unaffected. The perturbation caused by diamide in the membranes seems to affect primarily a step of the ATP hydrolysis mechanism that is common to both ATPase activities. The effectiveness of diamide seems to be the same when either Ca^2+^ and Mg^2+^, or Mg^2+^ alone are present during the reagent action. Reduction of disulfide bonds by DTE after diamide treatment restores the (Ca^2+^ + Mg^2+^)‐ATPase activity but is unable to take the Mg^2+^‐ATPase activity back to the original level.
The hypothesis is discussed that the redox state of one (or more than one) couple of SH close to each other and possibly connected to the active site, may be an important factor in optimizing the efficiency of Ca action on the (Ca^2+^ + Mg^2+^)‐ATPase.