Ultrastructure of native lipoprotein from Escherichia coli envelopes

The free form of the major lipoprotein from Escherichia coli cells envelopes has been purified to homogeneity by gentle extraction procedures and conventional chromatographic separations in a non-ionic detergent. The morphology of paracrystals obtained from homogeneous protein was investigated by low-dose electron microscopy. Electron diffraction of the paracrystals was consistent with alpha-helices arranged perpendicularly to the main cross-band with a periodicity of 20 nm.