期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 102, 期 2, 页码 315-320出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0406847102
关键词
x-ray diffraction; side-chain packing; structure; pi,pi bonding; beta-sheet interaction
The molecular structure of the amyloid fibril has remained elusive because of the difficulty of growing well diffracting crystals. By using a sequence-designed polypeptide, we have produced crystals of an amyloid fiber. These crystals diffract to high resolution (1 Angstrom) by electron and x-ray diffraction, enabling us to determine a detailed structure for amyloid. The structure reveals that the polypeptides form fibrous crystals composed of antiparallel,beta-sheets in a cross-beta arrangement, characteristic of all amyloid fibers, and allows us to determine the side-chain packing within an amyloid fiber. The antiparallel beta-sheets are zipped together by means of pi-bonding between adjacent phenylalanine rings and salt-bridges between charge pairs (glutamic acid-lysine), thus controlling and stabilizing the structure. These interactions are likely to be important in the formation and stability of other amyloid fibrils.
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