Protein Crystal Growth under a Forced Solution Flow(<Special Issue>The Forefront of Protein Crystal Growth)

Abstract

To obtain comprehensive understanding of the effects of a solution flow, we directly measured the velocities of individual elementary steps under a forced solution flow by laser confocal microscopy combined with differential interference contrast microscopy. We also investigated the defect density of four kinds of model protein crystals grown with/without forced solution flow, by slightly etching the crystal surfaces and observing etch pits. It was clarified that the growth of spiral steps is less affected by impurities, and at appropriate solution flow velocity, the microdefects could be reduced by the flow. It is one reason the flow improves crystal quality. On contrary the dislocation was increased by the flow in three cases of model proteins, which indicate that a dislocation may not be a serious defect for the crystal quality. Furthermore, it is possible that the growth mechanism shift from 2D nucleation growth mechanism to spiral growth mechanisms as a result of the increased defects induced by the solution flow could indirectly explain why forced solution flow improves crystal quality. In this paper, we introduce our recent studies about protein crystal growth under the forced solution flow.