Globin

globin [′glō·bən]

(biochemistry)

Any of a class of soluble histone proteins obtained from animal hemoglobins.

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Globin 

the albuminous part of the complex protein hemoglobin, which includes four globin chains. Up to 30 percent of the proteinaceous nitrogen of globin is found in the diamino acids (arginine, lysine, and histidine). This is also characteristic of the histones; however, in contrast to the latter, globin contains little tyrosine. The isoelectric point of globin is 7.5; it is readily soluble in water but is precipitated by alcohol or acetone. The bond between heme and globin is stable and broken only in an acidic environment. After detachment of the heme, the protein loses its native properties. The rate of synthesis of globin in the body is very high, owing to the frequent replacement of the erythrocytes. The synthesis of globin takes place at the sites where the erythrocytes are formed; in animals having nucleated erythrocytes, globin synthesis may be observed directly in the erythrocytes of the blood. Genetically induced anomalies in globin synthesis determine some “molecular” blood diseases, such as sickle-cell anemia and Mediterranean anemia. In some cases the difference of anomalous globin consists in the replacement of just one amino acid in the polypeptide chain.

A. A. BOLDYREV