Microtubules atomic structure

The first structural location of the taxane binding site [42] placed it in the interprotofilament space, thus supporting the biochemical results. However, this changed when the first high resolution 3D structure of the paclitaxel-tubulin complex was solved by electron-crystallography of a two-dimensional zinc-induced tubulin polymer [5]. The fitting of this structure into a three-dimensional reconstruction of microtubules from cryoelectron microscopy allowed a pseudo atomic resolution model of microtubules [43] in which the paclitaxel binding site was placed inside the lumen of the microtubules hidden from the outer solvent. 

The structural analyses of tubulin monomers in microtubules or flagellin monomers in flagella at atomic resolution are now in progress. The design of these monomers will be made clear very soon. 

Another molecular mode of action of furanocoumarins is related with protein modification. Proteins have multiple functions enzymes, transporters, ion channels, receptors, microtubules, structural proteins, etc. Conformational changes alter their properties and can prevent effective cross talk between proteins themselves and between proteins and other targets. Polyphenols can interact with proteins by forming hydrogen bonds and ionic bonds with electronegative atoms of the peptide bond or the positively charged side chains of basic amino acids, respectively. 

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