Tertiary structure of sickle cell hemoglobin and its functional significance

Precision scale models of sickle cell hemoglobin molecules indicate that the genetic substitution of valine for glutamic acid at the sixth position in the two β chains allows an intramolecular hydrophobic bond to form. This changes the conformation in such a way as to allow molecular stacking. Results of subjection of Hb S solution to temperature change and to propane are consistent with the presence of such a bond. Examination of sickled erythrocytes in a magnetic field and in polarized light indicates that the Hb S molecules are aligned in situ . Filaments interpreted as hollow cables of six Hb S monofilaments have been demonstrated by electron microscopy.