NR AELK
AU Gasset,M.; Baldwin,M.A.; Fletterick,R.J.; Prusiner,S.B.
TI Perturbation of the secondary structure of the scrapie prion protein under conditions that alter infectivity
QU Proceedings of the National Academy of Sciences of the United States of America 1993 Jan 1; 90(1): 1-5
PT journal article
AB Limited proteolysis of the scrapie prion protein (PrPsc) generates PrP 27-30, which polymerizes into amyloid. By attenuated total reflection-Fourier transform infrared spectroscopy, PrP 27-30 polymers contained 54% beta-sheet, 25% alpha-helix, 10% turns, and 11% random coil; dispersion into detergent-lipid-protein-complexes preserved infectivity and secondary structure. Almost 60% of the beta-sheet was low-frequency infrared-absorbing, reflecting intermolecular aggregation. Decreased low-frequency beta-sheet and increased turn content were found after SDS/PAGE, which disassembled the amyloid polymers, denatured PrP 27-30, and diminished scrapie infectivity. Acid-induced transitions were reversible, whereas alkali produced an irreversible transition centered at pH 10 under conditions that diminished infectivity. Whether PrPsc synthesis involves a transition in the secondary structure of one or more domains of the cellular prion protein from alpha-helical, random coil, or turn into beta-sheet remains to be established.
IN Nach der proteolytischen Abspaltung eines kleineren Proteinteils polymerisiert das Scrapieprionprotein zu amyloiden Strukturen. In den Polymeren scheinen die verkürzten Prionproteine zu 54% aus Beta-Faltblättern, zu 25% aus Alphahelices, zu 10% aus Kertwendungen und zu 11% aus variablen Abschnitten zu bestehen. Ein großer Teil der Faltblätter scheint sich intermolekular zu stabilisieren. Nach einer Dispersion mit Detergentien bleiben die Sekundärstrukturen und die Infektiosität erhalten. Erst nach Auflösung der Polymere und Denaturierung der Prionproteine nimmt die Infektiosität ab. Während Säuren nur vorübergehend wirken, führen pH-Werte um 10 zu irreversiblen Umlagerungen und vermindern die Infektiosität.
MH Animal; Brain/*microbiology; Centrifugation, Density Gradient; Electrophoresis, Polyacrylamide Gel; Endopeptidase K; Hamsters; Hydrogen-Ion Concentration; Prions/*chemistry/isolation & purification/pathogenicity; *Protein Conformation; Protein Denaturation; *Protein Structure, Secondary; Serine Endopeptidases; Solubility; Spectrophotometry, Infrared; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.
AD Department of Neurology, University of California, San Francisco 94143.
SP englisch
PO USA
OR Prion-Krankheiten G