Fig. 5: Heme binds to the His50 residue on α-Syn forming a peroxidase-positive complex.
a Stern-Volmer plot and double log plot (inset) obtained from the steady-state quenching and binding of TMR-5-maleimide-tagged α-Syn-G132C with heme, KD = 0.591 μM (datasets = 6). b Greek-key β-sheet alignment of the fibril core with the potential heme-binding residues (Tyr: in red; His: in yellow). Inset shows magnified view. c Kinetic traces for peroxidase activity monitored for the α-Syn WT-heme complex (datasets = 3). d The aggregation behaviour of the histidine mutant H50Q is unaltered in presence of heme as observed using ThT fluorescence. e–f AFM micrographs depict that H50Q aggregates into fibrils even in the presence of heme. Scale bars represent 500 nm. g The H50Q mutant shows no binding with heme, as observed from the absence of any quenching of TMR-tagged H50Q/G132C by heme (datasets = 3). All error bars are ±SEM.
