Aggregation and Fibrillation of Bovine Serum Albumin.
From: Centre for Insoluble Protein Structures (inSPIN) at Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
Biochimica et biophysica acta
- Publish Date: Sep 2007
- ISSN: 0006-3002
- Volume: 1774
- Issue: 9
- Pages: 1128-38
- Medium: Print
- Language: English
- Citation (JAMA): Holm Nikolaj K, Jespersen Stine K, Thomassen Lise V, et al. Aggregation and Fibrillation of Bovine Serum Albumin.. Biochim. Biophys. Acta Sep 2007;1774:1128-38
Abstract
The all-alpha helix multi-domain protein bovine serum albumin (BSA) aggregates at elevated temperatures. Here we show that these thermal aggregates have amyloid properties. They bind the fibril-specific dyes Thioflavin T and Congo Red, show elongated although somewhat worm-like morphology and characteristic amyloid X-ray fiber diffraction peaks. Fibrillation occurs over minutes to hours without a lag phase, is independent of seeding and shows only moderate concentration dependence, suggesting intramolecular aggregation nuclei. Nevertheless, multi-exponential increases in dye-binding signal and changes in morphology suggest the existence of different aggregate species. Although beta-sheet content increases from 0 to ca. 40% upon aggregation, the aggregates retain significant amounts of alpha-helix structure, and lack a protease-resistant core. Thus BSA is able to form well-ordered beta-sheet rich aggregates which nevertheless do not possess the same structural rigidity as classical fibrils. The aggregates do not permeabilize synthetic membranes and are not cytotoxic. The ease with which a multidomain all-alpha helix protein can form higher-order beta-sheet structure, while retaining significant amounts of alpha-helix, highlights the universality of the fibrillation mechanism. However, the presence of non-beta-sheet structure may influence the final fibrillar structure and could be a key component in aggregated BSA’s lack of cytotoxicity.
Mesh Headings (Keywords): Amyloid, Animals, Cattle, Cell Survival, Congo Red, Neuroblastoma, Protein Structure, Secondary, Serum Albumin, Bovine, Spectroscopy, Fourier Transform Infrared, Thiazoles, Trypsin, Tumor Cells, Cultured, X-Ray Diffraction
Check for Full Text / PubMed Unique Identifier (PMID): 17689306
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