BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Hemoglobin has a quaternary structure. It consists of two pairs of different proteins, designated the and chains. There are 141 and 146 amino acids in the and chains of hemoglobin, respectively. As in myoglobin, each subunit is linked covalently to a molecule of heme.

Detailed explanation-2: -Some proteins form assemblies (units) with other molecules – this is called the quaternary structure (Figure 14). Two examples are: haemoglobin which is an assembly of four globular proteins and the actin microfilament, composed of many thousands of actin molecules.

Detailed explanation-3: -Hemoglobin, on the other hand, is composed of multiple polypeptide subunits, each capable of binding and transporting one molecule of oxygen in the blood, thus giving it a quaternary structure.

Detailed explanation-4: -The structure for hemoglobin is very similar to myoglobin except that it has a quaternary structure due to the presence of four protein chain subunits. Actually, there are two pairs of similar chains-two alpha types and two beta types. Each protein chain subunit contains a heme group with the iron attached.

Detailed explanation-5: -Proteins with a quaternary structure can be classified into homomultimeric, that is, proteins that have identical subunits, and heteromultimeric, which are proteins with different types of subunits.