Investigating the Effect of Impurities on Macromolecule Crystal Growth in Microgravity

Abstract

Chicken egg-white lysozyme (CEWL) crystals were grown in microgravity and on the ground in the presence of various amounts of a naturally occurring lysozyme dimer impurity. No significant favorable differences in impurity incorporation between microgravity and ground crystal samples were observed. At low impurity concentration the microgravity crystals preferentially incorporated the dimer. The presence of the dimer in the crystallization solutions in microgravity reduced crystal size, increased mosaicity, and reduced the signal-to-noise ratio of the X-ray data. Microgravity samples proved more sensitive to impurity. Accurate indexing of the reflections proved critical to the X-ray analysis. The largest crystals with the best X-ray diffraction properties were grown from pure solution in microgravity.

Direct Observation of Adsorption Sites of Protein Impurities and Their Effects on Step Advancement of Protein Crystals

“…[17][18][19][20][21][22][23][24] Generally, impurities are considered to exhibit their effects on the growth process after they adsorb on a crystal surface. Thus, to fully comprehend the mechanisms of impurity effects, one has to observe in situ both (1) dynamics of elementary steps and (2) adsorption of impure molecules on a crystal surface, at a molecular level.…”

Impurity effects of lysozyme molecules specifically labeled with a fluorescent reagent on the crystallization of tetragonal and monoclinic lysozyme crystals

“…In protein crystallization, impure proteins whose molecular structures are closely related to that of a target protein negatively impact the quality of protein crystals [1][2][3]. There have been many studies of the impurity effects of structurally related proteins, such as sequentially heterogeneous proteins [4][5][6][7][8], oligomers [1][2][3][9][10][11][12][13], proteolysis products [14], oxidized proteins [15], glycoproteins [16,17], etc.…”

Enhancement and suppression of protein crystal nucleation due to electrically driven convection

“…Thus, the suppression of solution convention in the microgravity environment aboard spacecraft has served as the basis for elucidation of the role of the solute and impurity transport towards the interface for the growth and quality of protein and small molecule crystals [7][8][9]. Magnetic fields have been used to understand the role of molecular ordering in the crystallization processes [10].…”