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The thermal unfolding and domain structure of $Na^{+}/K^{+}$-exchanging ATPase.
| Content Provider | Scilit |
|---|---|
| Author | Grinberg, Asya V. Gevondyan, Natalia M. Grinberg, Natalia V. Grinberg, Valerij Y. |
| Copyright Year | 2001 |
| Description | Journal: Journal of Biological Inorganic Chemistry 1 1 Enzymes: ATP phosphohydrolase $(Na^{+}/K^{+}$-exchanging; EC 3.6.3.9). The thermal unfolding and domain structure of $Na^{+}/K^{+}$-ATPase from pig kidney were studied by high-sensitivity differential scanning calorimetry (HS-DSC). The excess heat capacity function of $Na^{+}/K^{+}$-ATPase displays the unfolding of three cooperative domains with midpoint transition temperatures $(T_{d}$) of 320.6, 327.5, 331.5 K, respectively. The domain with $T_{d}$ = 327.5 K was identified as corresponding to the β subunit, while two other domains belong to the α subunit. The thermal unfolding of the low-temperature domain leads to large changes in the amplitude of the short-circuit current, but has no effect on the ATP hydrolysing activity. Furthermore, dithiothreitol or 2-mercaptoethanol treatment causes destruction of this domain, accompanied by significant disruption of the ion transporting function and a 25% loss of ATPase activity. The observed total unfolding enthalpy of the protein is rather low (≈ 12 $J·g^{−1}$), suggesting that thermal denaturation of $Na^{+}/K^{+}$-ATPase does not lead to complete unfolding of the entire molecule. Presumably, transmembrane segments retain most of their secondary structure upon thermal denaturation. The binding of physiological ligands results in a pronounced increase in the conformational stability of both enzyme subunits. |
| Ending Page | 5036 |
| Starting Page | 5027 |
| ISSN | 2573508X |
| e-ISSN | 14321327 |
| DOI | 10.1046/j.0014-2956.2001.02436.x |
| Journal | Journal of Biological Inorganic Chemistry |
| Issue Number | 19 |
| Volume Number | 268 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 2001-10-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: Journal of Biological Inorganic Chemistry Na K Atpase Differential Scanning Calorimetry |
| Content Type | Text |
| Resource Type | Article |
| Subject | Biochemistry Inorganic Chemistry |
