The optical activity of lysozyme crystals.
The components of the gyration tensor of the enzyme lysozyme were measured by using the HAUP method: g11 = -0.90 x 10(-5) and g33 = 1.05 x 10(-5) at 303.4 K and a wavelength of 4880 A. The optical rotatory powers along the a and c axes in the same conditions were calculated: rho a = -21.3 and rho c = -24.8 degrees cm-1. The optically active property of lysozyme is strange in that, although it contains a considerable quantity of alpha-helices (about 30%), the rotatory powers are unexpectedly small in magnitude, one order of magnitude less than those of quartz and with very large anisotropy. A conceptual consideration of this phenomenon is given. In order to assess the difference between the structures in both crystalline and solution states, the chirality index r was calculated to be 0.16. This value indicates that the structural change of lysozyme from the solution into the crystalline state is expressed by an increase of 19% in optical activity. From the NMR results [Smith et al. (1993), J. Mol. Biol. 229, 930-944], it is anticipated that the r value reflects the increased constraint in atomic motion in the side chains of exposed amino acid residues in the crystalline state.
Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Tokyo, Japan.
J
J
Kobayashi
T
T
Asahi
M
M
Sakurai
I
I
Kagomiya
H
H
Asai
H
H
Asami
D000818:Animals; D016880:Anisotropy; D002645:Chickens; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D013237:Stereoisomerism
D009113:Muramidase