The hemoglobins in genetics and evolution / Vernon M. Ingram.

Ingram, Vernon Martin, 1924-

Date:: 1963

Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The hemoglobins in genetics and evolution / Vernon M. Ingram. Source: Wellcome Collection.

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or less spherical subunit (Perutz et al., 1960). The complete hemoglobin molecule, the tetramer, has a molecular weight of around 67,000. It seems likely that most vertebrate hemoglobins are made up in this way, with the exception of the hemoglobins from cyclostomes. Hemoglobin is considered to be a compound protein in the sense that it is composed of the protein globin and of four heme groups; these are molecules composed of protoporphyrin rings each containing at the center an iron atom. Each of the four subunits contains therefore one peptide chain together with its heme group. It is the iron atom (Fe ++ ) at the center of each heme group which is functionally the most important part of the molecule, since it is here that oxygen molecules attach themselves reversably during the oxygenation and deoxygenation of hemoglobin in its normal physiological role. THE HEMOGLOBIN TYPES The normal adult human hemoglobin (hemoglobin A or Hb A) is often written as cc^ß^ (Figure 2-1) to show that it is composed of two FIGURE 2-1. The different types of human hemoglobins Included are two examples of abnormal hemoglobins which are peculiar in having four identical subunits; they are discussed in chapters 3 and 4. a peptide chains and two ß peptide chains. The superscript A shows that the molecule is of the genetically normal, adult type. The human fetus on the other hand has a different type of hemoglobin (reviewed in White and Beaven, 1959) which can be readily distinguished chemically, but which has the same overall molecular complexity. Human fetal hemoglobin is composed of four peptide chains: two a polypeptide Adult Feta I Hemoglobin H /5 4 Hemoglobin Barts

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