320 BIOCHEMICAL GENETICS 



(It should be noted that some confusion occurs in the earlier literature regarding which 

 peptides are in the alpha and beta chains of human hemoglobins ; see Hunt and Ingram 619 

 for schematic representation of correct assigment for alpha and beta chains of human 

 hemoglobins.) 



The observations that chemical alterations occur in both the alpha and beta chains 

 support earlier suggestions by Schwartz et al. 1180 and Smith and Torbert 1220 that per- 

 haps there are two hemoglobin loci in man, one controlling the sequence of amino 

 acids in the alpha chain and the other controlling the sequence of amino acids in the 

 beta chain. A mutation may affect one or the other of these loci. Hunt 616 and Jones 

 et al. 667 established that the alpha chain of F and A hemoglobins are similar but F 

 hemoglobin has a modified beta chain, called gamma, suggesting that separate loci 

 exist for the synthesis of alpha, beta, and gamma chains of adult and fetal hemoglobins. 

 A 2 hemoglobin apparently differs from A in several peptides. 1291 



More recently, it has been found by Jones et al. 668 that hemoglobin H lacks alpha 

 chains. A fetal counterpart of hemoglobin H, Bart's hemoglobin, that also lacks alpha 

 chains has been reported, 620 and further investigations have shown that it is composed 

 of four gamma chains. 699 Thus, there is suggestive evidence, at least, for the presence 

 of many different loci which control hemoglobin synthesis in man 



SUMMARY 



Methods commonly used in studies of mammalian hemoglobins are surveyed 

 briefly. They include moving-boundary and zone electrophoresis, ultracentrifugation, 

 alkali denaturation, crystallography and solubility determinations, and amino-acid, 

 sulphydryl, end-group, and peptide analyses. Immunologic and spectrophotometric 

 techniques, and oxygen- and carbon monoxide-combining capacity, which generally 

 have more special applications, are not discussed in this review. The methods are 

 described in such a way as to give the reader an idea of the facilities required for each 

 analysis, and detailed descriptions are cited. It is hoped that the material presented 

 will help the reader to choose the methods most suited to his own investigation and 

 facilities. 



DISCUSSION 



Dr. Burdette : The discussion of Dr. Popp's paper will be opened by Dr. Elizabeth 

 Russell who also is engaged in some interesting studies on murine hemoglobins. 



Dr. Russell: First let me congratulate Dr. Popp for making clear a great deal of 

 complexity. I hasten to add that I do not pose as one who can tell a great deal about 

 murine hemoglobins, because I am still very much a student in this area. I agree 

 completely with Dr. Popp that multiple approaches from many different angles 

 will be essential to understand how genes are acting in producing the varying 

 hemoglobins found in mice. 



