Amyloidosis is caused by an abnormal deposition and accumulation of protein aggregates in tissues. How do proteins adopt and maintain a stable folded structure? What features of the protein amino acid sequence determine the stability of the folded structure? How does disruption of that structure lead to protein deposition diseases such as amyloidosis, Alzheimer's disease, and Parkinson's disease?

How do proteins adopt and maintain a stable folded structure? What features of the protein amino acid sequence determine the stability of the folded structure?

Proteins are formed by three-dimensional structures (twisted, folded or rolled over themselves) determined by the sequence of amino acids which are linked by peptide bonds. Among these bonds, what determines the most stable conformation of proteins is their tendency to maintain a native conformation, which are stabilized by chemical interactions such as: disulfide bonds, H bonds, ionic bonds and hydrophobic interactions.

How does disruption of that structure lead to protein deposition diseases such as amyloidosis, Alzheimer's disease, and Parkinson's disease?

The accumulation of poorly folded proteins can cause amyloid diseases, a group of several common diseases, including Alzheimer's disease and Parkinson's disease. As the human being ages, the balance of protein synthesis, folding and degradation is disturbed, which causes the accumulation of poorly folded proteins in aggregates, which can manifest itself in the nervous system and in peripheral tissues. The genes and protein products involved in these diseases are called amyloidogenic and all of these diseases have in common the expression of a protein outside its normal context. In all these diseases, protein aggregation can be caused by mere chance, by protein hyperphosphorylation, by mutations that make the protein unstable, or by an unregulated or pathological increase in the concentration of some of these proteins between cells. These imbalances in concentration can be caused by mutations of the amyloidogenic genes, changes in the amino acid sequence of the protein or by deficiencies in the proteasome.