作者: Anders Malmendal , Anders Malmendal , Sara Linse , Thom Leiding , Mikael Lund
DOI: 10.1021/JACS.1C01925
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摘要: Electrostatic interactions play crucial roles in protein function. Measuring pKa value perturbations upon complex formation or self-assembly of e.g. amyloid fibrils gives valuable information about the effect electrostatic those processes. Site-specific determination by solution NMR spectroscopy is challenged high molecular weight fibrils. Here we report a pH increase during fibril α-synuclein, observed using three complementary experimental methods: electrode measurements water; colorimetric changes fluorescent indicator; and chemical shift for histidine residues state spectroscopy. A significant was detected water, on average 0.9 units from 5.6 to 6.5, showing that protons are taken up formation. The upshift used calculate change apparent pKaave acidic residues, which found at least 1.1 unit due Metropolis Monte Carlo simulations were performed comparable system also showed proton uptake Fibril moreover leads binding capacitance. Parallel studies mutant with five charge deletions C-terminal tail revealed smaller formation, (0.5 average) values residues. We conclude connected density α-synuclein.