CD spectroscopy of τ constructs and τ polymers. CD spectra were obtained at 50 μM protein concentrations in 10 mM NH_{4} acetate at RT, in the absence or presence of 50 μM heparin and/or 50% TFE. (*A*) hτ23 monomers (circles), dimers (triangles), and assembled PHFs (solid line) show similar CD curves with or without heparin (filled or open symbols). (*B*) K19 monomers (without heparin, open circles; with heparin, filled circles) and dimers (without heparin, open triangles; with heparin, filled triangles; after aggregation, solid line). (*C*) PHF43 monomers (without heparin, open circles; with heparin, filled circles) and dimers without heparin (open triangles) and after aggregation (solid line). (*D*) PHF8 (without heparin, open circles; with heparin, filled circles) and PHF6 (without heparin, open triangles; with heparin, filled triangles). (*E*) Three peptides derived from PHF43, but not including 306-311 (^{313}VDLSKVTSK^{321}; without heparin, open circles; with heparin, filled circles; ^{318}VTSKCGSLGNIHHKPGGG^{335} without heparin, open triangles; with heparin, filled triangles; ^{335}GQVEVKSE^{342}, without heparin, open squares; with heparin, filled squares). (*F*) K19 (open circles) and PHF43 dimers (open triangles) and PHFs (K19, filled circles; PHF43, filled triangles) in the presence of 50% TFE.

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