302 



BIOCHEMICAL GENETICS 



of theoretical interest to hemoglobin chemists. The structural arrangement of the 

 four globin units 524 ' 650 ' 651, 652 ' 1065 ' 1210 has been approached by subjecting mixtures 

 of electrophoretically distinguishable hemoglobins to conditions of low or high pH 

 to dissociate hemoglobin into half-molecules and subsequently to allow the half-mole- 

 cules to reassociate at neutral pH. The mixtures of reassociated molecules are then 

 analyzed by the moving-boundary technique or other methods, that is, paper, starch-gel, 

 and agar-gel electrophoresis or column chromatography can be used, for presence of 

 fractions other than the two original components. Presumably, half-molecules of 

 structurally similar hemoglobins can hybridize upon molecular reassociation at neutral 

 pH. Hybridization of human and canine hemoglobin is reported in the latter two 



Fig. 40. Comparison of murine carbonmonoxyhemoglobins analyzed by moving- 

 boundary ELECTROPHORESIS. 



... *rr t*t 



Patterns were photographed after eight hours of electrophoresis; phosphate buffer, 

 ionic strength 0.1, pH 7.5, 158 volts, and 20 milliamps. 

 Left (A). Single hemoglobin of strain C57BL mice. 

 Right (B). Diffuse hemoglobin of strain 101 mice. 



studies cited above, suggesting that canine hemoglobin contains configurational analogs 

 of the alpha and beta chains of human hemoglobins. If the ionic change on the poly- 

 peptide chains of the hemoglobin differ, it may be possible to establish the plane of 

 cleavage of the dissociated half-molecules. The results obtained with human hemo- 

 globin indicate that the hemoglobin molecule dissociates into non-identical half- 

 molecules at low pH, 1210 the two alpha chains separating as a unit from the two beta 

 chains; however, at high pH the hemoglobin molecule dissociates into identical half- 

 molecules. 524 Each of the half-molecules of hemoglobin will dissociate further into 

 two subunits, but the reaction is irreversible since such units will not reassociate at neutral 

 pH as do the half-molecules. 524 • 616 



Zone electrophoresis. — A more compact and less expensive instrument than that 

 required for moving-boundary electrophoresis was necessary before electrophoretic 



