homework21.
Abstract:
Bovine spongiform encephalopathy (BSE) and human Creutzfeldt-Jakob disease (CJD) are among the most
notable central nervous system degenerative disorders caused by prions. CJD may present as a sporadic,
genetic, or infectious illness. Prions are transmissible particles that are devoid of nucleic acid and seem to be
composed exclusively of a modified protein (PrPSc). The normal, cellular prion protein (PrPC) is converted
into PrPSc through a posttranslational process during which it acquires a high beta-sheet content. It is thought
that BSE is a result of cannibalism in which faulty industrial practices produced prion-contaminated feed for
cattle. There is now considerable concern that bovine prions may have been passed to humans, resulting in a
new form of CJD.
2.
How many papers is referecned in Medline, on line biomedical abstract service, about prion?
1306
How many is concerning its structure?
167
Can you find the paper describe the structure of mouse prion?
Please show its abstract on your homepage.
Abstract:
The 'protein only' hypothesis states that a modified form of normal prion protein triggers infectious
neurodegenerative diseases, such as bovine spongiform encephalopathy (BSE), or Creutzfeldt-Jakob
disease (CJD) in humans. Prion proteins are thought to exist in two different conformations: the 'benign'
PrPcform, and the infectious 'scrapie form', PrPsc. Knowledge of the three-dimensional structure of PrPc is
essential for understanding the transition to PrPsc. The nuclear magnetic resonance (NMR) structure of the
autonomously folding PrP domain comprising residues 121-231 (ref. 6) contains a two-stranded antiparallel
beta-sheet and three alpha-helices. This domain contains most of the point-mutation sites that have been
linked, in human PrP, to the occurrence of familial prion diseases. The NMR structure shows that these
mutations occur within, or directly adjacent to, regular secondary structures. The presence of a beta-sheet in
PrP(121-231) is in contrast with model predictions of an all-helical structure of PrPc (ref. 8), and may be
important for the initiation of the transition from PrPc to PrPsc.