Properties of the α and β Chains of Hemoglobin Prepared from Their Mercuribenzoate Derivatives by Treatment with 1-Dodecanethiol

A novel, simple, and rapid procedure is described for the regeneration of "native" α and β polypeptide chains of human hemoglobin from their mercuribenzoate derivatives. The main feature of the method is the controlled emulsification of the mercuribenzoate derivatives with the water-insoluble thiol, 1-dodecanethiol. The regenerated chains show the theoretical number of —SH groups per heme, are essentially homogeneous in gel electrophoresis, and, when mixed in equimolar amounts, rapidly produce a compound which is indistinguishable from hemoglobin A in gel electrophoresis and in its reaction with oxygen. Sedimentation analyses reveal single boundaries for the individual chains and their equimolar product, with sedimentation coefficients in agreement with previously published values. The enthalpy of the reaction of the individual regenerated chains with oxygen has been determined and found to be -13.5 kcal per mole, a value very close to that reported for the oxygenation of hemoglobin. This finding lends strong support to the notion that the heme-heme interaction, observed in the reaction of oxygen with hemoglobin, is largely an entropy effect.