Protein crystals orientation in a magnetic field

Abstract

Nucleation and crystal growth of hen egg-white lysozyme, bovine pancreatic trypsin inhibitor and porcine pancreatic -amylase were carried out in the presence of a magnetic ®eld of 1.25 T produced by small permanent magnets. Crystals were oriented in the magnetic ®eld, except when heterogeneous nucleation occurred. The orientation of protein crystals in the presence of a magnetic ®eld can be attributed to the anisotropic diamagnetic susceptibility of proteins resulting from the large anisotropy of the -helices due to the axial alignment of the peptide bonds.

Usual and unusual crystallization from solution

“…Moreover, crystal growth of benzophenone under high magnetic fields was reported recently [32]. A rapid calculation [29] shows that under a field of 1.25 T, 10 7 lysozyme molecules are required to counteract the thermal energy, indicating that individual molecules are not oriented in solution. Magnetic field has an effect on crystal orientation but not on nucleation.…”

“…It is only recently, that protein crystals have been nucleated and grown in the presence of a magnetic field [28][29][30][31]. Moreover, crystal growth of benzophenone under high magnetic fields was reported recently [32].…”

Orientation of growing crystals of Co- or Gd-containing L-threonine dehydrogenase by magnetic fields

“…In addition, magnetic levitation of the growing crystals at the air-solution interface or within the crystallizing solution in an inhomogeneous magnetic field that exerts an upward magnetization force also improves crystalline homogeneity [1][2][3]. However, the findings accumulated so far were based mainly on the observations on model proteins such as lysozyme and amylase [2][3][4][5].…”

Effect of various precipitants on the nucleation rate of tetragonal hen egg-white lysozyme crystals in an AC external electric field

“…Much research has been carried out with the aim of obtaining high-quality protein crystals by applying an external field, such as an electric [1][2][3][4][5][6][7][8][9][10][11][12][13][14], magnetic [15,16], electromagnetic [17][18][19][20][21][22][23], or hydrodynamic [24,25] field. The technique employing an external electric field is expected to be of particular utility, because it is possible not only to control the nucleation rate but also to enhance the crystal quality [1,12] using this method.…”