With the advent of combinatorial chemistry and the extensive libraries of potential
drugs produced from it, there is a growing need for rapid sensitive, high-throughput
screening for drug potency. Microtubules are important targets for anticancer agents,
and new antimicrotubule compounds are of continued interest in drug development. The
in vitro potency of antimicrotubule drugs may be evaluated by measuring the extent
of tubulin assembly. The extent of polymerization is proportional to the turbidity
of the solution, which usually has been measured as apparent absorption. The turbidity
method has inherent problems that hinder its adaptation to a high-throughput format,
such as a requirement for high protein concentrations and a high coefficient of variation.
We present here a high-throughput assay for antimicrotubule activity in which fluorescence
is used to monitor microtubule assembly. Both assembly-inhibiting and assembly-promoting
compounds can be evaluated. The assay is rapid and easy to perform, and the data are
reliable, with good accuracy and reproducibility.