Answer:
1. The prosthetic group of hemoglobin and myoglobin is heme.
2.The organic ring component of heme is porphyrin ring.
3. Under normal conditions, the central atom of heme is Iron (Fe2+).
4. In deoxyhaemoglobin the central iron atom is displaced 0.4 A out of the plane of the porphyrin ring system.
5.The central iron atom has six bonds: four to nitrogen atoms in the porphyrin, one to a histidine residue and one to oxygen.
Explanation:
1. The heme is the prosthetic group common to both the hemoglobin and myoglobin. It is made up of a central iron ring.
2. The porphyrin ring is the organic component of the heme that surrounds the iron ring. Its based on a tetrapyrole ring called porphin commonly found in other biomolecules such as cytochrome and chlorophyll in plants
3. Iron (Fe2+) is central to the heme structure. It has the ability to bind to an oxygen molecule at a time. This gives the protein- hemoglobin the ability to bind to 4 oxygen molecules at a time.
4. Deoxyhaemoglobin is simply a reduced form of hemoglobin which has lost oxygen molecule in red blood cells. It is purple blue in colour.
5. In the middle of the porphyrin ring, the iron binds to 4 nitrogen atoms. 2 free binding sites are available on either side of the plane heme structure with histidine surounding the heme molecule.
