20.500.12556/RUL-155598 Amyloid fibrils of stefin B show anisotropic properties Human stefin B, a member of the cystatin family of cysteine protease inhibitors, tends to form amyloid fibrils under relatively mild conditions, which is why it is used as a model protein to study amyloid fibrillation. Here, we show for the first time that bundles of amyloid fibrils, i.e., helically twisted ribbons, formed by human stefin B exhibit birefringence. This physical property is commonly observed in amyloid fibrils when stained with Congo red. However, we show that the fibrils arrange in regular anisotropic arrays and no staining is required. They share this property with anisotropic protein crystals, structured protein arrays such as tubulin and myosin, and other anisotropic elongated materials, such as textile fibres and liquid crystals. In certain macroscopic arrangements of amyloid fibrils, not only birefringence is observed, but also enhanced emission of intrinsic fluorescence, implying a possibility to detect amyloid fibrils with no labels by using optical microscopy. In our case, no enhancement of intrinsic tyrosine fluorescence was observed at 303 nm; instead, an additional fluorescence emission peak appeared at 425 to 430 nm. We believe that both phenomena, birefringence and fluorescence emission in the deep blue, should be further explored with this and other amyloidogenic proteins. This may allow the development of label-free detection methods for amyloid fibrils of different origins. nano-sized object bundle of amyloid fibrils birefringence intrinsic fluorescence label-free imaging delci nanovelikosti skupki amiloidnih fibril dvolomnost intrinzična fluorescenca slikanje brez označevanja true false true Angleški jezik Slovenski jezik Članek v reviji 2024-04-08 10:23:09 2024-04-08 10:23:10 2024-10-02 13:41:42 0000-00-00 00:00:00 2023 0 0 10 str. iss. 4, art. 3737 Vol. 24 Feb. 2023 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 577.112 1661-6596 10.3390/ijms24043737 142086659 ijms-24-03737.pdf ijms-24-03737.pdf 1 A4219990861F41B1A614153271DBA1B1 86e31389969f12ef81a2b63c5ec2f0ff66b7a04574f8a4506c9b7441572b8de1 b6b7632d-f581-11ee-937a-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=182566 https://www.mdpi.com/1422-0067/24/4/3737 1 3cc4dd3a-f581-11ee-937a-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=182565 Fakulteta za matematiko in fiziko Medicinska fakulteta 0 0 0