Protective or Deteriorative Effect of Zinc Ions on Protein Misfolding: A New Insight into Amyloidogenic Disease

Insulin as a small molecule with 51 residues is an interesting model useful in studying protein misfolding of neurodegenerative amyloid proteins. Investigating zinc effects on insulin misfolding and aggregation triggered by 80% ethanol is the main objective of the present work. Using different methods of turbidity measurement, examining thioflavin T fluorescence changes during insulin aggregation, and conducting Far-UV circular dichroism spectroscopy of the process, we studied insulin aggregations in the presence of micromolar and millimolar concentrations of zinc ions to shed light on the mechanism of misfolding in these circumstances. Our findings confirmed that millimolar concentrations of zinc protect insulin integrity against acidic pH, high temperature, and 80% concentration of ethanol as misfolding inducer. We hypothesize zinc to be of therapeutic importance in amyloidogenic disease in case it is applicable.