Question 1: Do I have to stabilize the microtubules I’ve made with taxol?

Answer 1: We strongly recommend using taxol to stabilize the microtubules created with the fluorescent microtubules biochem kit (Cat. # BK007R).  Microtubules are stable at room temperature when they are in the presence of a 10-20 mM taxol solution. In this state, the microtubules are stable for at least 24 h at room temperature (20-24°C).  In the absence of taxol, microtubules are very sensitive to temperature variations. For example, microtubules stored at 4°C in the absence of taxol will depolymerize into tubulin heterodimers very rapidly. Thus, if you are performing experiments with non-taxol stabilized microtubules you should keep the temperature at 37°C.

Question 2: Can I alter the length of microtubules produced using the fluorescent microtubules Biochem Kit?

Answer 2: Yes, microtubules that are longer or shorter in average length than those resulting from the standard polymerization conditions described in the kit manual (Cat. # BK007R) can easily be produced.  Below is a table that gives the polymerization conditions that are required to create microtubules of a given average length. Components of the reaction should be added in the order that they appear from left to right.  It should be noted that all tubulin stock solutions that you are working with (including those that you create of a given stoichiometry) are at an initial protein concentration of 10 mg/ml