Two depictions of the molecular double strand
        found in deoxy sickle-cell hemoglobin crystals.Figure 4

Molecular Biology of Hemoglobin in Sickle-Cell Anemia

    The first figure shows a sickle-cell hemoglobin fiber, with heme groups in red and the valine residue in blue. The fiber consists of two strands: note that the valine residues make intermolecular contacts between the two strands,so as to stabilize the structure.

    The second  figure is a close-up stereo diagram of the contact: the regions labelled E & F are in the  beta-globin subunit of a hemoglobin one strand, and the A & H regions are in the other fiber. The yellow Val residue on the right-hand molecule fits into a pocket formed by amino acids 84, 85, 87, & 88 in the left hand molecule.

[To view the stereo figure: gaze at a point between the two drawings and let your eyes cross; blink to superimpose the two out-of-focus images into one in-focus image].

Figures © 2009 by W. Royer; text material © 2014 by Steven M. Carr