Estimation of flexural rigidity of proteinaceous filaments like microtubules and Actin.

Microtubules are hollow fibers with outer and inner diameters of 30 and 18 nm respectively and length of about 100mm. They play central role in cell physiology. They form the moving cores of cilia and flagella, they are the tracks along which intracellular proteins move and they actively take part in the intracellular signal transduction. What mechanical properties the microtubules possess in order that it can perform many different structural roles. Here we will show how we can estimate the flexural rigidity of cellular fibers like microtubules.

Figure 32.1

From our discussion on bending of thin flexible rods, we can say that we can estimate flexural rigidity by clamping a microtubule of known length at one end while applying a known force to the other and measuring its deflection. However, here we will describe a technique to measure the bending of an unconstrained microtubule by thermal forces.