CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION DATA OF 2 DIFFERENTHUMAN LOW-DENSITY-LIPOPROTEIN (LDL) SUBFRACTIONS

Human LDL subfractions LDL-2 (d = 1.031-1.034 g/ml) and LDL-5 (d = 1.0 40-1.044 g/ml) were crystallized in two different crystal forms by usi ng polyethylene glycol as a precipitant. Both fractions were from one donor. Crystals of LDL-5 were yellow, hexagonal, and showed no dichroi sm. Crystals of LDL-2 were of the same color, had a rodlike shape with notches at both ends, and were highly dichroitic. LDL-2 crystals diff racted to a resolution of 29 Angstrom by using synchrotron radiation. Indexing in P1 resulted in preliminary parameters for the reduced cell of a 171 Angstrom, b = 438 Angstrom, c = 519 Angstrom, alpha = 102 de grees, beta = 99 degrees, gamma = 91. These dimensions are consistent with the size of LDL particles. Using Fourier transform infrared spect roscopy (FTIR) and agarose gel electrophoresis, we could further confi rm that the crystals consist of LDL. The FTIR spectrum showed bands ch aracteristic for lipids and protein. Dissolved crystals exhibited a mo bility similar to native LDL in agarose gels and could be stained with anti-human apolipoprotein B (apoB). (C) 1997 Wiley-Liss, Inc.