Crystallization and preliminary X-ray analysis of a low density lipoprotein from human plasma.
Single crystals of human plasma low density lipoprotein (LDL), the major transport vehicle for cholesterol in blood, have been produced with a view to analysis of the three-dimensional structure by x-ray crystallography. Crystals with dimensions of approximately 200 x 100 x 50 microm have been reproducibly obtained from highly homogeneous LDL particle subspecies, isolated in the density ranges d = 1.0271-1. 0297 g/ml and d = 1.0297-1.0327 g/ml. Electron microscopic imaging of ultrathin-sectioned preparations of the crystals confirmed the existence of a regular, quasihexagonal arrangement of spherical particles of approximately 18 nm in diameter, thereby resembling the dimensions characteristic of LDL after dehydration and fixation. X-ray diffraction with synchrotron radiation under cryogenic conditions revealed the presence of well resolved diffraction spots, to a resolution of about 29 A. The diffraction patterns are indexed in terms of a triclinic lattice with unit cell dimensions of a = 16. 1 nm, b = 39.0 nm, c = 43.9 nm; alpha = 96.2 degrees, beta = 92.1 degrees, gamma = 102 degrees, and with space group P1.
Institute of Biophysics and X-ray Structure Research, Austrian Academy of Sciences, A-8010 Graz, Austria. fibrlagg@mbox.tu-graz.ac.at
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R
Prassl
J M
JM
Chapman
F
F
Nigon
M
M
Sara
S
S
Eschenburg
C
C
Betzel
A
A
Saxena
P
P
Laggner
D018360:Crystallography, X-Ray; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood / Q000737:chemistry*; D008854:Microscopy, Electron; D011487:Protein Conformation
D008077:Lipoproteins, LDL