Effects of a Magnetic Field on Lysozyme Crystal Nucleation and Growth in a Diffusive Environment

Tetragonal hen egg white lysozyme crystals were grown in agarose gel under the influence of a 7 T homogeneous and static magnetic field. The use of agarose, gels, and polymer solutions avoids crystal sedimentation and buoyancy-driven convection providing a diffusive mass transport environment. Under these conditions, 100% of lysozyme crystals grown in 0.02% (w/v) agarose can be oriented by a 7 T magnetic field. When the agarose concentration was increased, the number of oriented crystals decreased. The results are explained by the compromise between the effect of the magnetic field and the chemical effects due to the interaction between protein and agarose, because it is known that agarose modifies the nucleation rate of lysozyme crystals. When the chemical effect of agarose was removed, it appears clear that a homogeneous and constant magnetic field influences both nucleation and growth of lysozyme tetragonal crystals in a convection-free environment. Both effects depend on supersaturation and exposure time.