Two unrelated proteins aggregate in UHT milk over a period of months to form amyloid fibrils. The post Milk Study Improves Understanding ...
Coaggregation of κ-Casein and β-Lactoglobulin Produces Morphologically Distinct Amyloid Fibrils.
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Small (Weinheim an der Bergstrasse, Germany), ISSN: 1613-6829, Vol: 13, Issue: 14
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- Repository URL:
- http://ro.uow.edu.au/smhpapers/4662; https://publications.csiro.au/rpr/pub?list=SEA&pid=csiro:EP166238
- Biochemistry, Genetics and Molecular Biology; Materials Science; Engineering
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The unfolding, misfolding, and aggregation of proteins lead to a variety of structural species. One form is the amyloid fibril, a highly aligned, stable, nanofibrillar structure composed of β-sheets running perpendicular to the fibril axis. β-Lactoglobulin (β-Lg) and κ-casein (κ-CN) are two milk proteins that not only individually form amyloid fibrillar aggregates, but can also coaggregate under environmental stress conditions such as elevated temperature. The aggregation between β-Lg and κ-CN is proposed to proceed via disulfide bond formation leading to amorphous aggregates, although the exact mechanism is not known. Herein, using a range of biophysical techniques, it is shown that β-Lg and κ-CN coaggregate to form morphologically distinct co-amyloid fibrillar structures, a phenomenon previously limited to protein isoforms from different species or different peptide sequences from an individual protein. A new mechanism of aggregation is proposed whereby β-Lg and κ-CN not only form disulfide-linked aggregates, but also amyloid fibrillar coaggregates. The coaggregation of two structurally unrelated proteins into cofibrils suggests that the mechanism can be a generic feature of protein aggregation as long as the prerequisites for sequence similarity are met.