Electron microscopic studies on the initial process of lysozyme crystal growth

The initial process of lysozyme crystallization has been investigated by ne gatively stained electron microscopy. In the initial process of crystalliza tion, two steps were distinguished by the appearance of associating protein molecules. One is the formation of the short threads, and the other the fo rmation of the spherical structure (looks like a rice-ball). From among the mass of the rice-balls, larger structure appears. Some of them show the ar rangement of molecules as a crystalline lattice. The spacing between the mo lecules agrees with one of the lattice constants known for the tetragonal l ysozyme crystals. The rice balls may be taken into crystals as essential gr owth units. Similarly, the thread-like structures may be the unit to form t he rice-balls that appear in the next step. (C) 1999 Elsevier Science B.V. All rights reserved.