Structures of apo GCase grown under different conditions. Overlay of two monomers in asymmetric unit exhibiting distinct loop 1 structures (α-helical or extended). (A) Left C2, pH 5.5; middle C3, pH 4.5; right C4, pH 4.5 (soaked). Ribbon diagrams are colored using a rainbow corresponding to increasing thermal factor from blue (low B-factor) to red (high B-factor). (B) Superposition of structures in (A)-(C) in loop 1, loop 2 region. Red: α-helical loop 1, blue: extended loop 1conformation.