Fig. 6. Evidence for the hexagonal bilayer (HBL) structure of Methanoaricia
dendrobranchiata hemoglobin. (A) Negatively stained electron microscope
image of M. dendrobranchiata hemoglobin. The dark areas are stain.
The protein of the molecular complex appears pale. The hemoglobin molecular
complexes are in various orientations. The top and side views (indicated)
appear to be similar to the top (sixfold) and side (twofold) views of other
annelid hemoglobins. Scale bar, 200 nm. (B) An image of a typical top view
taken from the electron microscope image in A. Scale bar, 30 nm. (C)
Rotational frequency analysis of image B showing the strong sixfold symmetry
expected of an HBL. (D) The sixfold rotationally Fourier-filtered image of B.
The sub-structure, such as the density in the middle and the holes within the
six subunits, is similar to that of other HBLs. Scale bar, 30 nm.
