SAXS analysis of Hsp90 variants. (a–c) P(r) curves for WT and mutant Hsp90 in the absence of nucleotide (a) or the presence of 4 mM ATP-γS (b) or ATP (c). Bottom, mutants for which significant differences in the P(r) were observed; top, mutants for which no differences or only minor differences were observed. Black, WT; yellow, A107N; blue, Δ8; green, T22I; purple, R346S; gray, R380A; red, E33A.