Microtubules (MTs) are 25 nm protein nanotubes with wall comprised of protofilaments built from αβ-tubulin and have a negative charge (surface charge density ? -0.87 e/nm2). MTs are involved in cell division, intracellular trafficking, establishment and maintenance of cell shape. The previous studies show that tubulin with multivalent cations/ cationic polymer complex forms ring and tubular structure without GTP according to charge interaction. In order to control these structure, by using transmission electron microscopy (TEM) we used polylysine (surface charge density ? 2.12 e/nm2) and observed the effect of polylysine molecular weight, concentration (R = concentration of polylysine/concentration of tubulin) and Taxol on the assembly structure of tubulin and polylysine. Assembled with polylysine, tubulin forms various structures which includes the single protofilament ring (SPR), double protofilament ring (DPR), tubulin sheet, bundle of protofilaments (PFs), single walled tubulin tube (SWTT) and double walled tubulin tube (DWTT). For 500 - 2000 Da polylysine, TEM show DPR at R = 0.25 and DWTT at R ?? 0.5. MT like, PFs bundle, tubulin sheet at R = 0.05 - 0.25 and DWTT at R ≥ 0.375 are observed in the presence of Taxol. For 150k - 300k Da, TEM show DPR, short DWTT at R = 0.1 - 0.2, short PFs at R = 0.2 and SPR, SWTT at R ≥ 0.25. MT like, PFs bundle, tubulin sheet at R = 0.01 - 0.05, short DWTT at R = 0.1 - 0.25, SWTT at R ≥ 0.25 are observed in the presence of Taxol. PEGylated-polylysine (PEG-PL) has been used, resulting in similar assembly structures. DPR, SPR, DWTT and SWTT are observed at higher R than the case of polylysine. PEG-PL prevent polylysine induced aggregation of tubulin tubes. This study contributes to quantify nano structure using x-ray scattering and provide an insight into how we can functionalize tubulin based nanotubes for drug delivery system.
