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Abstract The degree by which metalloproteins partially regulate net charge (Z) upon electron transfer (ET) was recently measured for the first time using “protein charge ladders” of azurin, cytochrome c, and myoglobin [Angew. Chem. Int. Ed.2018,57(19), 5364–5368;Angew. Chem.2018,130, 5462–5466]. Here, we show that Cu, Zn superoxide dismutase (SOD1) is unique among proteins in its ability to resist changes in net charge upon single ET (e.g., ΔZET(SOD1)=0.05±0.08 per electron, compared to ΔZET(Cyt‐c)=1.19±0.02). This total regulation of net charge by SOD1 is attributed to the protonation of the bridging histidine upon copper reduction, yielding redox centers that are isoelectric at both copper oxidation states. Charge regulation by SOD1 would prevent long range coulombic perturbations to residue pKa’s upon ET at copper, allowing SOD1’s “electrostatic loop” to attract superoxide with equal affinity (at both redox states of copper) during diffusion‐limited reduction and oxidation of superoxide.
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Supercharging Prions via Amyloid‐Selective Lysine Acetylation
Abstract Repulsive electrostatic forces between prion‐like proteins are a barrier against aggregation. In neuropharmacology, however, a prion's net charge (Z) is not a targeted parameter. Compounds that selectively boost prionZremain unreported. Here, we synthesized compounds that amplified the negative charge of misfolded superoxide dismutase‐1 (SOD1) by acetylating lysine‐NH3+in amyloid‐SOD1, without acetylating native‐SOD1. Compounds resembled a “ball and chain” mace: a rigid amyloid‐binding “handle” (benzothiazole, stilbene, or styrylpyridine); an aryl ester “ball”; and a triethylene glycol chain connecting ball to handle. At stoichiometric excess, compounds acetylated up to 9 of 11 lysine per misfolded subunit (ΔZfibril=−8100 per 103subunits). Acetylated amyloid‐SOD1 seeded aggregation more slowly than unacetylated amyloid‐SOD1 in vitro and organotypic spinal cord (these effects were partially due to compound binding). Compounds exhibited reactivity with other amyloid and non‐amyloid proteins (e.g., fibrillar α‐synuclein was peracetylated; serum albumin was partially acetylated; carbonic anhydrase was largely unacetylated).
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- PAR ID:
- 10231516
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 60
- Issue:
- 27
- ISSN:
- 1433-7851
- Format(s):
- Medium: X Size: p. 15069-15079
- Size(s):
- p. 15069-15079
- Sponsoring Org:
- National Science Foundation
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