The intermolecular interaction of lysozyme and concanavalin A were investigated by atomic force microscopy, respectively. The mean size and polydispersity of both lysozyme and concanavalin A aggregates in solution under crystallization and non-crystallization conditions as the function of protein concentration and temperature were studied by dynamic light scattering method. The results showed that the intermolecular interaction of protein molecules had a strong effect on nucleation during protein crystal growth. Because the van der Waals force among concanavalin A molecules was stronger than that among lysozyme molecules, the growth unit of concanavalin A crystal could not appear quickly after the precipita-tor was mixed with concanavalin A solution, which caused the longer crystal growth time than that for ly-sozyme.

Key words: intermolecular interaction, concanavalin A, lysozyme, aggregate, crystal growth