Prions
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| − | Not all infectious diseases are transmitted by bacteria or [[Virus|viruses]]. Some neurological diseases, such as [[Creutzfeldt-Jaakob disease (CJD)|Creutzfeldt- | + | Not all infectious diseases are transmitted by bacteria or [[Virus|viruses]]. Some neurological diseases, such as [[Creutzfeldt-Jaakob disease (CJD)|Creutzfeldt-Jakob disease (CJD)]] or mad cow disease are in fact caused by agents called Prions''', '''which are of similar size to viruses but are made up of only [[Protein|protein]] <ref>J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company</ref>. These diseases are can be called Prion diseases or [[Transmissible spongiform encephalpathies|transmissible spongiform encephalpathies]] (TSE) <ref>http://www.who.int/bloodproducts/tse/en/</ref>. |
Prionshave these characteristics: | Prionshave these characteristics: | ||
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#"The protein is largely or completely derived from a cellular protein called PrP, that is normally present in the brain" <ref>J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company</ref>. | #"The protein is largely or completely derived from a cellular protein called PrP, that is normally present in the brain" <ref>J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company</ref>. | ||
| − | So an aggregated form of a [[ | + | So an aggregated form of a [[Protein|protein]] (that is already present in the brain) is the infectious agent in prion diseases <ref>J. M. Berg et al. (2007) p 54, Biochemistry, Sixth edition, New York, W.H. Freeman and Company</ref>. |
The pathalogic mechanism of prions is often associated with structural change. Exogenous prions cause the endogenous host proteins to undergo a structural change, rendering them functionless or harmful. | The pathalogic mechanism of prions is often associated with structural change. Exogenous prions cause the endogenous host proteins to undergo a structural change, rendering them functionless or harmful. | ||
| − | Prions size and structure enable them to resistance to: | + | Prions size and structure enable them to resistance to: |
| − | *[[ | + | *[[Proteases|proteases]] |
| − | *heat (not in 100 celsius) | + | *heat (not in 100 celsius) |
| − | *radiation | + | *radiation |
| − | *fixative treatments ([[ | + | *fixative treatments ([[Formaldehyde|formaldehyde]]) |
| − | If only the [[ | + | If only the [[Secondary structure|secondary]], [[Tertiary structure|tertiary]] and [[Quaternary Structure|quaternary]] structure is destroy the prion can fold back to the prion after the influence of the substance |
| − | examples of prion disease: | + | examples of prion disease: |
| − | *[[ | + | *[[Scrapie|scrapie]] (sheep) |
| − | *[[Bovie spongiform encephalopathy|Bovie spongiform encephalopathy]] (BSE) [[ | + | *[[Bovie spongiform encephalopathy|Bovie spongiform encephalopathy]] (BSE) [[Mad cow disease|mad cow disease]] |
*[[Kuru|Kuru]] (transmitted by ritual cannibalism) | *[[Kuru|Kuru]] (transmitted by ritual cannibalism) | ||
Revision as of 20:56, 3 December 2017
Not all infectious diseases are transmitted by bacteria or viruses. Some neurological diseases, such as Creutzfeldt-Jakob disease (CJD) or mad cow disease are in fact caused by agents called Prions, which are of similar size to viruses but are made up of only protein [1]. These diseases are can be called Prion diseases or transmissible spongiform encephalpathies (TSE) [2].
Prionshave these characteristics:
- "The transmissible agent consists of aggregated forms of a specific protein" [3].
- These protein aggregates cannot be degraded by the agents that degrade most other proteins [4].
- "The protein is largely or completely derived from a cellular protein called PrP, that is normally present in the brain" [5].
So an aggregated form of a protein (that is already present in the brain) is the infectious agent in prion diseases [6].
The pathalogic mechanism of prions is often associated with structural change. Exogenous prions cause the endogenous host proteins to undergo a structural change, rendering them functionless or harmful.
Prions size and structure enable them to resistance to:
- proteases
- heat (not in 100 celsius)
- radiation
- fixative treatments (formaldehyde)
If only the secondary, tertiary and quaternary structure is destroy the prion can fold back to the prion after the influence of the substance
examples of prion disease:
- scrapie (sheep)
- Bovie spongiform encephalopathy (BSE) mad cow disease
- Kuru (transmitted by ritual cannibalism)
References
- ↑ J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company
- ↑ http://www.who.int/bloodproducts/tse/en/
- ↑ J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company
- ↑ J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company
- ↑ J. M. Berg et al. (2007) p 53, Biochemistry, Sixth edition, New York, W.H. Freeman and Company
- ↑ J. M. Berg et al. (2007) p 54, Biochemistry, Sixth edition, New York, W.H. Freeman and Company
