The chain present in myoglobin is globin.
Myoglobin is a protein found primarily in muscle tissue where it stores oxygen. Its structure is relatively simple compared to hemoglobin. Here's a breakdown:
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Single Polypeptide Chain: Myoglobin consists of only one polypeptide chain, known as globin. This is in contrast to hemoglobin, which has four subunits.
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Globular Protein: The globin chain folds into a compact, globular shape.
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Alpha Helices: The globin chain is composed of approximately 153 amino acids and contains eight alpha-helices, labeled A through H. These helices are crucial for forming the hydrophobic pocket where the heme group binds.
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Heme Group: The globin chain encapsulates a heme group, which contains an iron atom (Fe2+). This iron atom is the site where oxygen binds reversibly. The globin protein's structure is crucial for preventing the iron from oxidizing to Fe3+, which cannot bind oxygen.
In summary, the functional unit of myoglobin is the single globin polypeptide chain associated with a heme group. This simple structure allows myoglobin to efficiently bind and release oxygen within muscle tissue.
