Prion protein amyloid, structural models

Inadequate crystallinity in the amyloid deposits of the PrP form of human prion protein or of any of its mutated and truncated forms limits the details of the p-structure available from X-ray crystallography. A recent report of electron crystallography of two-dimensional crystals of the proteinase K-treated PrP form giving essentially the sequence from residues 90 to 231, however, is available. The model focusing on the P-structure appears in top view in Figure 7.36A and in side view in Figure 7.36B. The... 

These results indicate that is it possible to change the fold of a protein by changing a restricted set of residues. They also confirm the validity of the rules for stability of helical folds that have been obtained by analysis of experimentally determined protein structures. One obvious impliction of this work is that it might be possible, by just changing a few residues in Janus, to design a mutant that flip-flops between a helical and p sheet structures. Such a polypeptide would be a very interesting model system for prions and other amyloid proteins. 

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