Globin chains, of hemoglobin

The thalassemias are characterized by the absence or reduced synthesis of one or more of the four globin chains of hemoglobin. 

Will Sichel has sickle cell anemia caused by a point mutation in his DNA that changes the sixth amino acid in the p-globin chain of hemoglobin from glutamate to valine. What difference would you expect to find in the chemical bonds formed by these two amino acids ... 

Niprisan is a combined extract of four plants traditionally used in Nigeria to prevent sickle-cell disease (SCD) (lyamu, 2003 Wambebe, 2001). SCD is caused by a point mutation in the gene encoding for the beta globin chain of hemoglobin, distorting red blood cells into an... 

Abnormal hemoglobulins can be detected by electrophoresis, as shown in Figure 7.4, which includes a pattern observed in /3+-thalassemia and one in a newborn with a-thalassemia (possibly HbH disease). It should also be mentioned that, unless there is a coexisting hemoglobin abnormality resulting from a point mutation or crossover problem, the globin chains of classic a- and /3-thalassemia are perfectly normal. It is usually the quantities of either the a or the /3 chains that are decreased. Some frameshifts have been found near the terminus of the /3 chain that lead to frameshift mutations in certain areas. 

This work uncovered the fact that a substitution of the amino acid alanine for valine at position 126 in the /3-chain of hemoglobin occurred in a hemato-logically normal adult of Lebanese extraction. The variation /3-globin was initially observed and subsequently purified by reverse-phase liquid chromatography (see Fig. 2-5). Also LC was used to isolate the variant tryptic peptide of /3-T13 that had alanine replacing the valine at amino-acid residue position 126. This is shown in Figure 2-6. (Peptide mapping is discussed later in this chapter.)... 

A. Diseases related to abnormal hemoglobin Sickle cell anemia results from a point mutation (GAG to GTG) that causes valine to replace glutamate at position 6 in the P-globin chain. In hemoglobin Wayne, deletion of a base causes a frameshift that produces the wrong sequence of amino acids in the chain beyond position 127. 

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