Van der Waals surface of the spinach chloroplast c14-ring with polar/apolar interfaces and additional electron densities. (A) The outer surface of the c-ring is shown. (B) Section clip of the c14-ring shows inner surface. Red dashed lines mark the putative positions of polar/apolar interfaces, which are different for inner and outer surfaces of the c-ring. The thickness of the apolar region is 45.8 Å and 32.6 Å for the inner and outer surfaces, respectively. Amino acids are colored according to their hydrophobicity and active centers Glu61 are colored red. The additional electron densities inside the c-ring are colored as deep green mesh, which shows the density map (Fo – Fc) at 3σ. Stroma of the chloroplast is on the top; thylakoid lumen is on the bottom of the picture.