[Protein crystals and tubuli bundles in yeast cells. II. Isolation, biochemical and electron microscopical...

A purified fraction of crystals stabilized with Cd2+ is prepared from Saccharomyces carlsbergensis protoplasts by means of differential centrifugation. As proved by negative staining the crystals are hexagonal with well preserved surface which in its turn also reveals a hexagonal fine structure. Crystals are digestible by pronase (1 mg/m) in phosphate buffer (pH 7.4). The molecular weight of protein subunits is 38000+/-300D. Amino acid composition of the crude crystal protein is similar to that of microtubular protein (MTP) from brain and sperm, except that lysin content is much higher. The crystal protein exhibits more differences, however, after purification by preparative gel electrophoresis. The level of glycine, alamine, and valine is increased, whereas that of glutamic acid is decreased.