Effect of Protein Molecular Anisotropy on Crystal Growth

• Published in: Crystal growth & design 2008-12, Vol.8 (12), p.4262-4267
• Main Authors: Hondoh, Hironori, Nakada, Toshitaka
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystalline state (including molecular motions in solids); Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Solid surfaces and solid-solid interfaces; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Theory of crystal structure, crystal symmetry; calculations and modeling
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg800694j

We have measured the difference in the growth rates of the (010) and (01̅0) polar faces of hen egg-white lysozyme monoclinic crystals using optical microscopy, and observed the micro-topography of these faces with atomic force microscopy. Because of the lack of a rotational axis perpendicular to the b-axis, these two opposite faces are not symmetry related. The growth rate of the (010) face was faster than the (01̅0) face at supersaturation levels of 0.84−3.5. The surface free energy of the step on the (010) face is calculated to be 8.9 ± 1.3 × 10−4 J/m2. Using atomic force microscopy to examine the crystal faces, the steps on the (010) face were smooth, straight, and parallel to the a- and c-axes, whereas the steps on the (01̅0) face were rough and a complex shape even with highly purified lysozyme. The complex shape of the steps on the (01̅0) face indicates the presence of adsorbed molecules on the terraces of the steps. The relatively slow growth of the (01̅0) face may be explained by the adsorption of wrongly oriented lysozyme molecules with this face.