THE SUSCEPTIBILITY OF PURE TUBULIN TO HIGH MAGNETIC-FIELDS - A MAGNETIC BIREFRINGENCE AND X-RAY FIBER DIFFRACTION STUDY

The orientational behavior of microtubules assembled in strong magneti c fields has been studied. It is shown that when microtubules are asse mbled in a magnetic field, they align with their long axis parallel to the magnetic field. The effect of several parameters known to affect the microtubule assembly are investigated with respect to their effect on the final degree of alignment. Aligned samples of hydrated microtu bules suitable for low-resolution x-ray fiber diffraction experiments have been produced, and the results obtained from the fiber diffractio n experiments have been compared with the magnetic birefringence exper iments. Comparisons with earlier fiber diffraction work and small-angl e x-ray solution scattering experiments have been made.