MORPHOLOGICAL APPEARANCES OF K88AB FIMBRIAE AND OPTICAL DIFFRACTION ANALYSIS OF K88 PARACRYSTALLINE STRUCTURES

K88ab fimbriae are filamentous protein structures at the surface of ce rtain enterotoxigenic Escherichia coli strains. Electron microscopy an alysis of K88ab fimbriae showed that these structures have different m orphological appearances dependent on the medium in which cells expres sing these fimbriae or in which purified fimbriae were suspended. Thin and curled structures, thin and flexible fimbriae, a wider and rigid form of the fimbriae, and, in addition, paracrystalline structures wer e detected. Optical diffraction analysis of the paracrystalline struct ures indicated a helical conformation of K88ab fimbriae.