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

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"