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Showing 2 results for Amyloid Fibrils
Seyyed Abolghasem Ghadami,
Volume 14, Issue 2 (5-2023)
Abstract
Transthyretin (TTR) is a highly conserved 55 kDa homotetrameric protein that exists in several vertebrate species including humans, bacteria, nematodes, and plants. Previous studies have shown a direct interaction between TTR and amyloid beta (Aβ) (the causative agent of Alzheimer's disease), which leads to the inhibition of Aβ aggregation, fibrillar destruction, or both. In recent years, evidence has shown that the oligomeric species of Aβ formed by the aggregation process are more toxic than mature fibrils. Studies have shown that such an oligomeric mediator is modulated by interaction with TTR. However, the exact mechanism of binding of Aβ to TTR has not yet been determined. In this study, after the purification of human transthyretin protein, the inhibitory effects of TTR on the formation of Aβ were shown in different ways, and finally, the role of hydrophobicity interactions in the chaperone activity of TTR was investigated with the help of protein surface hydrophobicity (PSH) measurement studies. The Scatchard diagram for quantitative measurement of PSH indicates an increase in the hydrophobicity of TTR after binding to oligomeric forms of Aβ. The results presented in this research provide insight into the nature and interactions involved in the initial stages of fibril formation in Aβ and its interaction with TTR. The results showed that hydrophobic interactions probably play a role in the binding between TTR and Aβ. Considering the similarity of amyloid formation systems, the described findings of this study can provide a deeper understanding of the pathology of amyloid diseases.
Sabereh Saremi, Khosro Khajeh, Bahareh Dabirmanesh, Mahdi Ayyari,
Volume 15, Issue 3 (6-2024)
Abstract
Alpha-synuclein protein (α-syn) is the main factor known in Parkinson's disease. The expression of this protein has challenges. One of these challenges is the presence of protein in bacterial pellet. Studies have shown that the expression of proteins with tags such as small ubiquitin-like modifier (SUMO) increases the expression in the soluble phase, therefore the expression of α-syn with this sequence was investigated to increase the protein in the soluble phase. It has also been shown in studies that SUMOylation has an inhibitory effect on fibrillation, also in this study the effect of the SUMO on alpha-synuclein fibrillation was investigated. The α-syn gene was cloned with SUMO-tag. Nickel sepharose column was used to purify the protein, and dialysis was performed and fibrillation was checked by fluorescence emission of Thioflavin for 72 hours and was observed that the protein with SUMO sequence has a higher expression level, and 95% of the protein is in the soluble phase. On the other hand, it was shown that the SUMO sequence has an inhibitory effect on the process of amyloid fibril formation. The results obtained from previous studies showed that the binding of the SUMO sequence increases the expression and solubility of recombinant proteins. This study revealed that the presence of this sequence contributed to the protein expression level and the protein's presence in the solution phase. On the other hand, observations showed that this sequence has anti-fibrillation properties for proteins with amyloid properties, and in this study showed that SUMO prevents α-syn aggregation.
