Hybrid formation for liganded hemoglobins A and C at subzero temperatures

The kinetics of formation of the asymmetric carbon-monoxyhemoglobin hybrid (αβ)(A)(αβ)(C) from the parent molecules α2β2(A) and α2β2(C) have been studied by electrophoresis at subzero temperatures (down to -40°C) using as supporting media gels of acrylamide/methylacrylate in dimethyl sulfoxide/water mixtures. It has been found that in these media the rate of hybrid formation is markedly affected by pH and decreases by an order of magnitude between pH 7.3 and 8.3. At pH>10, t=-40°C, the hybrid between α2β2(A) and α2β2(C) is stable for several hours. A rapid thermal quenching of a mixture of α2β2(A) and α2β2(C) prevented hybrid formation during the time required to separate the 2 molecules.