314 



BIOCHEMICAL GENETICS 



f Symbols C and c ch indicate full color and chinchilla, respectively; symbols Hb C57BL and Hb SeC 

 indicate hemoglobin loci in strains C57BL and SeC, respectively. 



of hemoglobins obtained from test progeny also indicate that the diffuse-type hemo- 

 globins differ among some strains of mice (Popp, unpublished data). 



CHEMICAL ANALYSES 



The physical methods described in the foregoing section are used to identify 

 different hemoglobins in mammals and to study their mode of inheritance. Such 

 methods in themselves, however, do not reveal the details of molecular structure which 

 distinguish one hemoglobin from another. Analyses of the amino-acid composition 

 and sequence are required to elucidate these differences. Differences in the protein 

 chemistry of hemoglobin molecules, resulting from genie action, are of concern to bio- 

 chemical geneticists. Some of the equipment and methods described above are also 

 used for analysis of the composition of the hemoglobin molecule, with the principal 

 difference that the submolecular components are being analyzed and compared rather 

 than the native hemoglobin molecule. 



Amino-acid analysis 



Column chromatography, used for recognition of different hemoglobins, as 

 described earlier, is also used to separate the amino acids of hemoglobin hydrolysates. 

 The procedures of amino-acid determination on ion-exchange resins, developed by 

 Moore and Stein, 890, 892 has been applied by several investigators to assay the amino-acid 

 composition of hemoglobins. 647 Automatic recording apparatus 1209, 1259 provides 

 complete quantitative analyses within 24-72 hours. 



In a comparative analysis of human hemoglobins A, C, E, and F, Stein et al. 1272 

 observed that the amino-acid composition of these hemoglobins is similar except that 

 fetal hemoglobin contains an additional amino acid, isoleucine. Allen et al. 8 noted 

 a similar isoleucine difference between adult and fetal hemoglobin. Since different 



