The findings by University of Edinburgh may help in better understanding of neurodegenerative diseases such as Alzheimer's.
Amyloid fibres are rarely formed protein chains, which have been linked with dozens of diseases and are produced as a result of a genetic flaw or changes in body chemistry brought about by ageing.
When this happens, short fibres are formed which become sticky and attract copies of themselves, forming an endless chain. These chains spontaneously break, creating more filament ends to which more proteins attach.
Researchers have found that when protein levels are low, lots of short protein threads are formed. But when protein levels are high, this spontaneous breakage stops and most protein filaments remain long.
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Compared with harmful short protein fibres, long fibres do not appear to be damaging in the case of neurodegenerative diseases.
Researchers therefore believe that high levels of the protein - which lead to these longer chains - may actually be protective.
In addition to shedding light on disease, this insight into the protein chains may help scientists develop useful biomaterials, such as cell scaffolds, which are used for tissue engineering or to make artificial silk.
"Understanding how these protein chains form offers us insight not only into how diseases progress, but how we can produce controlled biomaterials for tissue engineering," MacPhee said.