User:Andy Maloney/Kinesin & Microtubule Page/Microtubule papers/Kinesin driven microtubule motility in the presence of alkaline earth metal ions indication for a calcium ion dependent motility.

Disclaimer

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

This paper talks about divalent cations and which is the best to use when looking at microtubules and kinesin.
Kinesin was purified from porcine brain.
Tubulin was purified from porcine brain.
Gliding velocities:
- With 0.5 mM MgCl₂
  - 0.60 µm/s ± 0.07 µm/s
- No divalent cations
  - 0.007 µm/s 0.002 µm/s
- With 2.5 mM CaCl₂
  - 26 µm/s
  - This value was calcium ion dependent and I'm quoting the highest value given.
  - Note that motility was restored when they added calcium.
- 0.5 mM SrCl₂
  - 0.025 µm/s
- BaCl₂
  - 0.014 µm/s
- 0.5 mM BeCl₂
  - 0.002 µm/s
  - It appears that beryllium just toasts microtubule motility even after getting rid of it in the chamber.
Gliding activity decreases with increasing atomic weight of the alkaline salt.
- This is interesting. Especially when you think about the paper discussing viscous load. Apparently, the heavier the sugar used to slow MTs down, the less you have to use of it. It would seem that also, the heavier the divalent salt you use, the slower the MTs will glide as well.
  - There may be something here about using heavy water or heavy oxygen water.
When any of the salts were combined with MgCl₂, motility was normal except for when BeCl₂ was combined with magnesium.
Hmm, they say that even sodium or potassium can sustain motility. But, it is really slow.
They do reference a paper that shows that kinesin will stop working if there is too much magnesium in solution, >10 mM.

If magnesium is present in solution, it doesn't matter the other types of divalent salts that may be there (except beryllium), the assay will work.