VSE knjižnice (vzajemna bibliografsko-kataložna baza podatkov COBIB.SI)
  • Probing the pH-dependent structural features of ▫$\alpha-KTx_{12.1}$▫, a potassium channel blocker from the scorpion Tityus serrulatus
    Oyama, Sérgio, jr. ...
    Potassium channels are widespread in living cells and are involved in many diseases. The scorpion toxin -KTx12.1 interacts with various K+ channels, suggesting its capacity to match diverse channel ... pores. It is recognized that tissue injuries may affect the pH at toxins site of action, thereby modulatingboth protein conformation and activity. To better understand its molecular mechanism of action, we studied -KTx12.1 using pH as a tool to explore its plasticity and NMR in combination with MD calculations to detect it. The toxin solution structure consists of an -helix and a triple-stranded -sheet stabilized by four disulfide bridges. The NMR results show, in addition, that His28 possesses an unusually low pKa of 5.2. The best set of protein conformers is obtained at pH 4.5, while at pH 7.0, the reduced number of NOEs resulting from a faster hydrogen exchange does not allow to reach a good structural convergence. Nonetheless, MD calculations show that the toxin structure does not vary significantly in that pH range, while conformational changes and modifications of the surface charge distribution occur when His28 is fully protonated. Moreover, essential dynamics analysis reveals variations in the toxinćs coherent motions. In conclusion, His28, with its low pKa value,provides -KTx12.1 with the ability to preserve its active conformation over a wide pH interval, thus expanding the range of cellular conditions wherethe toxin can fully exhibit its activity. Overall, the results further underline the role of histidine as a natural controller of proteinsć functionality.
    Vir: Protein science. - ISSN 0961-8368 (Vol. 14, št. 4, 2005, str. 1025-1038)
    Vrsta gradiva - članek, sestavni del ; neleposlovje za odrasle
    Leto - 2005
    Jezik - angleški
    COBISS.SI-ID - 3233562

vir: Protein science. - ISSN 0961-8368 (Vol. 14, št. 4, 2005, str. 1025-1038)
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