PRESERVATION OF 2-D CRYSTALS OF TUBULIN FOR ELECTRON CRYSTALLOGRAPHY

Zinc-induced sheets of tubulin are two dimensional crystalline polymer s that constitute an ideal sample for high resolution studies of tubul in by electron crystallography. We show that these 2-dimensional tubul in crystals can be stabilized by taxol against low-temperature depolym erization and degradation with time, easing the way for the preparatio n of electron microscopy samples. The preservation of the crystals to high resolution has been tested with different embedding media. While glucose-embedded samples diffract poorly, samples embedded in tannin c onsistently diffract to a resolution of at least 3.5 Angstrom. Even be tter results are obtained by embedding with a combination of tannin an d glucose, which improves the flatness of the crystals and allows the collection of isotropic high-resolution data from tilted specimens. (C ) 1995 Academic Press, Inc.