Question

Question 3 In deoxyhemoglobin Fe2* is high spin and five-coordinate, while in oxyhemoglobin six-coordinate Fe2+ is in the low spin state. Explain what the octahedral high and low spin states of six-coordinate Fe2+ are with the aid of energy diagrams. What is the structural significance of Fe2 being in the low spin state in oxyhemoglobin? Oxyhemoglobin and oxymyoglobin are both oxygen carriers in mammalian blood. Explain how they differ structurally and what their complementary roles are. [5 marks]

Answer 1

Answer: Both in deoxyhemoglobin and oxyhemoglobin they are exist as Fe2+ which eledronic conbegreradion es [Ar]3d • 48². According to Perretz mechanism the de oxyhemogloben es high spin Fe (II) atom, whose energy deaglemes 11 eg 114 11/11 d.g2 d2² In oxygen changes the oaks me On the plan Octahedral de system of legend day dyz diez a Crystal beild splitting energy diagra high span complex In oxygenated scale aree to transformation from T stale to R state, et is to changed into love spin complexe The energy diagram is eg 1111111_ 1111|1|11- bez dz TL 11 12 +28 Crystal beeld seletting energy drage der In deoxyhemoglobin the Fe2+ size is 0.78 Å which is too large to bit in the centre of porphyan ring. It is situated 07-08 Å above the plane distorted the bond around Fe. In oxygenated hemogloben the size of Fe2+ is 0 614, which changes the electronic structure as well When one he me group peaks one O₂, dree to contration of size et moves into the plane of the ring. Since they are hydrogen bonded, so they Chooges the conbormation too and hence inercase the asility to take O₂ molecule Doing so, the non planer strecture converted into planer structure. Mpoglobin is similar to one of the group of hemoglobin. Simply it is the one unit of hemoglobin. It is a mano meric protein whereas the hemoglobin is tetra. meric heme protein The role of hemoglobin is to transport my genbrom horor to body whereas the ho myoglobin transber meygen to the tissues cell. The reacions are bollows Lungs (grills Hb + 402 (HbO2) 4. Tissues Hb (02)4 +4 Mb – 4 Mb (0) 2 tlth Myogloben has greater asbenitz vor any gen as Compared to hemoglobin. So there is a tramber of oxygen oceness at the tissues. Basically myogloben stores Breygen at ougeles