PRE data from wild type (WT) alpha-synuclein (aS), family variants beta-synuclein (bS) and gamma-synuclein (gS), the Parkinson’s disease associated E46K mutation, and the low pH form of the protein, illustrating that the effects of sequence variations and environment on long-range structure can be evaluated qualitatively (14, 26, 27). Solid red lines represent the expected PRE effect based on a Gaussian chain model of the protein. Solid green lines in the E46K and pH3 plots are smoothed data from the wild type protein labeled at the same position (110) at neutral pH and are shown for ease of comparison. In this case, there is a correlation with a decrease (bS and gS) or increase (E46K and low pH) in long-range interactions and a concordant decrease (bS and gS) or increase (E46K and low pH) in aggregation propensity.