User:Andy Maloney/Kinesin & Microtubule Page/Osmotic stress/Inhibition of kinesin driven microtubule motility by polyhydroxy compounds

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Disclaimer

These are my notes. Please read the article before reading my notes.

Book

Micro- and nanostructures of biological systems : selected proceedings of the 1st symposium held at the Martin Luther University Halle-Wittenberg at Halle, October 4-5, 2000 / editors, Gerlinde Bischoff and Hans-Joachim Hein.

Notes

  • Microtubules moved in circular tracks and slowed down with the following chemicals:
    • Glycerol - 8 M stopped motility.
    • Sorbitol
    • Glucose
    • Sucrose
    • PEG 6000 & 20000
    • All experiments were done in a gliding motility fashion.
    • One experiment was done with kinesin coated beads and the same effect occurred.
    • Bohm notes that the percentage of circling microtubules was proportional to the concentration of additives.
  • Used porcine brain kinesin and tubulin, 40 µg/mL
  • The polymerized microtubules were formed with Taxol.
  • The motility buffer used was
    • 100 mM NaCl
    • 20 µM Taxol
    • 0.5 mM MgATP
  • They passivated the glass with bovine serum albumin at 5 mg/mL.
  • This is interesting, Bohm states that the molar concentration of the sugar required to slow the microtubules down by 50% decreases as the molecular weight of the sugar increases.
    • This means that the heavier the sugar, the less you need to add to slow the microtubules down.
  • What's interesting is that all the substances used to slow the microtubules down followed the same curve when plotted against the dynamic viscosity of the buffer.
  • Bohm states that viscosity cannot explain these effects. He does say that there is a possibility that the reason slowing occurs is because of the "hydrate shell" of the proteins.
  • "A limited ATP supply caused by the lowered diffusion rate at higher viscosity

also seems not to be a reason worth mentioning for the velocity decrease"