Catechol-induced covalent modifications modulate the aggregation tendency of α-synuclein: An in-solution and in-silico study.

Parkinson's disease (PD) stands as a challenging neurodegenerative condition characterized by the emergence of Lewy Bodies (LBs), intracellular inclusions within dopaminergic neurons. These LBs harbor various proteins, prominently including α-Synuclein (Syn) aggregates, implicated in disease pathology. A promising avenue in PD treatment involves targeting Syn aggregation. Recent findings from our research have shown that 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylethanol (DOPET) possess the ability to impede the formation of Syn fibrils by disrupting the aggregation process. Notably, these compounds primarily engage in noncovalent interactions with the protein, leading to the formation of off-pathway oligomers that deter fibril growth. Through proteolysis studies and mass spectrometry (MS) analysis, we have identified potential covalent modifications of Syn in the presence of DOPAC, although the exact site remains elusive. Employing molecular dynamics simulations, we delved into how DOPAC-induced covalent alterations might affect the mechanism of Syn aggregation. Our findings indicate that the addition of a covalent adduct on certain residues enhances fibril flexibility without compromising its secondary structure stability. Furthermore, in the monomeric state, the modified residue fosters novel bonding interactions, thereby influencing long-range interactions between the N- and C-termini of the protein.