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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
12
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pubmed:dateCreated |
1997-4-29
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pubmed:abstractText |
PrP(Sc) is known to be the major, if not the only, component of the infectious prion. Limited proteolysis of PrP(Sc) produces an N-terminally truncated polypeptide of about 142 residues, designated PrP 27-30. Recently, a recombinant protein (rPrP) of 142 residues corresponding to the Syrian hamster PrP 27-30 was expressed in Escherichia coli and purified (Mehlhorn et al., 1996). rPrP has been refolded into both alpha-helical and beta-sheet structures as well as various intermediates in aqueous buffers. The beta-sheet state and two pH-dependent alpha-helical states were characterized by CD and NMR. The alpha-helical conformation occurred only after the formation of an intramolecular disulfide bond, whereas the beta-sheet form was accessible either with or without the disulfide. Of the different alpha-helical forms studied, only those refolded in the pH range 5-8 were substantially soluble at physiological pH, exhibiting similar conformations and monomeric analytical sedimentation profiles throughout the above pH range. Furthermore, refolded alpha-rPrP showed NMR chemical shift dispersion typical of proteins with native conformations, although 2D NMR indicated large segments of conformational flexibility. It displayed a cooperative thermal denaturation transition; at elevated temperatures, it converted rapidly and irreversibly to the thermodynamically more stable beta-sheet form. Unfolding of alpha-rPrP by GdnHCl revealed a two-phase transition with a relatively stable folding intermediate at 2 M GdnHCl. The deltaG values were estimated to be 1.9 +/- 0.4 kcal/mol for the first phase and 6.5 +/- 1.2 kcal/mol for the second, consistent with a folding core surrounded by significant segments of flexible conformation. By NMR, alpha-rPrP(acid) isolated at pH 2 without refolding exhibited heterogeneous line widths, consistent with an acid-denatured molten globular state. We conclude that to the extent that rPrP constitutes a relevant folding domain of PrP(C), the various conformations exhibited by rPrP suggest that the PrP sequence may be intrinsically plastic in its conformations; indeed, portions of PrP(C) may possess a relatively open conformation which makes it susceptible to conversion into PrP(Sc) under appropriate conditions.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0006-2960
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
36
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
3543-53
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:9132005-Animals,
pubmed-meshheading:9132005-Chromatography, High Pressure Liquid,
pubmed-meshheading:9132005-Circular Dichroism,
pubmed-meshheading:9132005-Cricetinae,
pubmed-meshheading:9132005-Magnetic Resonance Spectroscopy,
pubmed-meshheading:9132005-Mass Spectrometry,
pubmed-meshheading:9132005-Mesocricetus,
pubmed-meshheading:9132005-Pliability,
pubmed-meshheading:9132005-Prions,
pubmed-meshheading:9132005-Protein Conformation,
pubmed-meshheading:9132005-Recombinant Proteins,
pubmed-meshheading:9132005-Spectroscopy, Fourier Transform Infrared,
pubmed-meshheading:9132005-Ultracentrifugation
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pubmed:year |
1997
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pubmed:articleTitle |
Physical studies of conformational plasticity in a recombinant prion protein.
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pubmed:affiliation |
Department of Neurology, University of California, San Francisco 94143, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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