a. heme group is nonplanar when it is not bound to oxygen; the iron atom is pulled out of the plane of the porphyrin, toward the histidine residue to which it is attached. This nonplanar configuration is characteristic of the deoxygenated heme group, and is commonly referred to as a "domed" shape. The valence electrons in the atoms surrounding iron in the heme group and the valence electrons in the histidine residue form "clouds" of electron density. (Electron density refers to the probability of finding an electron in a region of space.) Because electrons repel one another, the regions occupied by the valence electrons in the heme group and the histidine residue are pushed apart. Hence, the porphyrin adopts the domed (nonplanar) configuration and the Fe is out of the plane of the porphyrin ring . However, when the Fe in the heme group binds to an oxygen molecule, the porphyrin ring adopts a planar configuration and hence the Fe lies in the plane of the porphyrin ring.
b. The shape change in the heme group has important implications for the rest of the hemoglobin protein, as well. When the iron atom moves into the porphyrin plane upon oxygenation, the histidine residue to which the iron atom is attached is drawn closer to the heme group. This movement of the histidine residue then shifts the position of other amino acids that are near the histidine . When the amino acids in a protein are shifted in this manner (by the oxygenation of one of the heme groups in the protein), the structure of the interfaces between the four subunits is altered. Hence, when a single heme group in the hemoglobin protein becomes oxygenated, the whole protein changes its shape. In the new shape, it is easier for the other three heme groups to become oxygenated. Thus, the binding of one molecule of O2 to hemoglobin enhances the ability of hemoglobin to bind more O2molecules. This property of hemoglobin is known as "cooperative binding."
c. Role of BPG :-
The increase in amount of BPG present in the red blood cell, decrease the affinity of hemoglobin to oxygen and decrease in the amount of BPG present in red blood cell, increase the affinity of hemoglobin to oxygen.
biochemistry Question 2.(12 pts) O2 binding to Fe? in one subunit of hemoglobin changes the binding affinity of the...
O2 binding to Fe2+ in one subunit of hemoglobin changes the binding affinity of the other 3 subunits. a. Describe the change in the shape of the heme that results in O2 binding. b. How is the heme shape change communicated to the other subunits c. What is the role of Bisphosphoglycerate (BPG) in hemoglobin mediated oxygen transport?
Describe the T and R conformaions of hemoglobin with regards to: oxygen binding affinity; change in heme conformation upon binding to oxygen; effect that a conformational change in a single subunit has on other subunits (ex: cooperativitt)
biochemistry Question 3.(9 pts) You need to make up a 600 ml of a 40 mM solution of Citric acid DH 7.5 from a 1M stock of Citric acid pH 6.4. Citric acid pKa 6.4. Describe how you would make up this solution. Show work and all calculations Question 3.(9 pts) You need to make up a 600 ml of a 40 mM solution of Citric acid DH 7.5 from a 1M stock of Citric acid pH 6.4. Citric acid...
The mutation in hemoglobin at β82Lys→Asp results in lowered O2-binding affinity compared to normal hemoglobin. β82 is one of the residues that lines the 2,3-BPG binding site (see the figure above; β82 is adjacent to His143). Based on the location of this residue and the differences between Lys and Asp, suggest a rationale for the observed reduction in O2-binding affinity. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each...
biochemistry if you could please help me answer the following questions! EFT i 11) (6 pts) Which types of symmetry are possible for a protein with six (6) identical subunits? (Select all correct answers) a) cyclic C b) cyclic C3 c) dihedral D2 d) dihedral D e) octahedral o f) icosahedral ро, Yo₂ - pO₂+ Pso 12) (6 pts) What is the fractional saturation of oxygen binding to myoglobin when the partial pressure of oxygen is 1.5 torr and dissociation...
10. Write a one-page summary of the attached paper? INTRODUCTION Many problems can develop in activated sludge operation that adversely affect effluent quality with origins in the engineering, hydraulic and microbiological components of the process. The real "heart" of the activated sludge system is the development and maintenance of a mixed microbial culture (activated sludge) that treats wastewater and which can be managed. One definition of a wastewater treatment plant operator is a "bug farmer", one who controls the aeration...