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Updated: May 8, 2026
Directly Measuring Forces Within Reconstituted Active Microtubule Bundles
Published on: May 10, 2022
Measurement of in vitro microtubule polymerization by turbidity and fluorescence
Matthew Mirigian1, Kamalika Mukherjee, Susan L Bane
1Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland, USA.
Abstract:
Tubulin polymerization may be conveniently monitored by the increase in turbidity (optical density, or OD) or by the increase in fluorescence intensity of diamidino-phenylindole. The resulting data can be a quantitative measure of microtubule (MT) assembly, but some care is needed in interpretation, especially of OD data. Buffer formulations used for the assembly reaction significantly influence the polymerization, both by altering the critical concentration for polymerization and by altering the exact polymer produced-for example, by increasing the production of sheet polymers in addition to MT. Both the turbidity and the fluorescence methods are useful for demonstrating the effect of MT-stabilizing or -destabilizing additives.
Insights
Monitoring tubulin polymerization via turbidity or fluorescence offers quantitative insights into microtubule assembly. Careful interpretation is needed, as buffer conditions significantly impact polymerization and polymer structure.
Area of Science:
- Biochemistry
- Cell Biology
- Biophysics
Background:
- Tubulin polymerization is fundamental to microtubule (MT) dynamics.
- Accurate monitoring of MT assembly is crucial for understanding cellular processes.
Purpose of the Study:
- To evaluate turbidity (optical density) and fluorescence intensity methods for monitoring tubulin polymerization.
- To highlight the influence of buffer formulations on MT assembly.
Main Methods:
- Monitoring tubulin polymerization by measuring increases in optical density (OD).
- Monitoring tubulin polymerization by measuring increases in diamidino-phenylindole fluorescence intensity.
- Analyzing the impact of buffer composition on polymerization kinetics and polymer structure.
Main Results:
- Both OD and fluorescence methods provide quantitative data on MT assembly.
- Buffer formulations critically affect the critical concentration and polymer product (e.g., sheet polymers).
- Turbidity and fluorescence assays effectively demonstrate the effects of MT-modulating agents.
Conclusions:
- Turbidity and fluorescence are valuable tools for studying tubulin polymerization.
- Buffer composition is a key variable influencing MT assembly outcomes.
- These methods facilitate the assessment of microtubule-stabilizing and -destabilizing compounds.
