Molecular structure of the amyloid-forming protein kappa I Bre

The molecular structure of the amyloid-forming Bence-Jones protein kappa I Bre has been determined by X-ray crystallography at 2.0 Angstrom resolution . The fragment from the kappa chain of immunoprotein contains 107 amino aci d residues, and polymerizes in the crystal form into a giant helical spiral , surrounding a cylinder of water 50 Angstrom in diameter with a repeat of 77.56 Angstrom, containing 12 kappa molecules, plus another 12 molecules fr om neighboring parallel spirals. The resulting structure has many features which have been found or suggested from studies on the protein fibrils foun d in amyloid deposits, From the results of the X-ray crystal structure a hy pothesis is presented for the structure and formation of the amyloid fibril .