Biochem: Hemoglobin and Homotropic Allosteric Modulator Essay

Submitted By bonita22
Words: 483
Pages: 2

CH 301 Optional Examination 20 Points
Due date is Exam Day, Tuesday, May 7 at 1 p.m.
(Based on Chapter 5 & 6)
Q.1. (2 Points) a. What is the structure of BPG? * 1,3-Bisphosphoglycerate is the conjugate base of 1,3-bisphosphoglyceric acid. It is phosphorylated at the number 1 and 3 carbons.
b. (4 Points) Explain using graphs, how BPG binding affects binding of oxygen. Include reactions. * HbBPG + O2 ⇌ HbO2 + BPG
By binding to deoxyhemoglobin, 2,3-BPG stabilizes the T state conformation, making it harder for oxygen to bind hemoglobin and more likely to be released to adjacent tissues.
c. (4 Points) How your body will respond to the sudden change of your decision to go to top of the mountain, which is at 2000 meter high from the sea level? * The delivery of oxygen to the tissue will be reduced; within hours concentration of BPG from the blood will start to rise. When more BPG binds to the hb the affinity of o2 will decreased; therefore oxygen will be released in the tissues and you will feel ok.

Q.2.(4 Points) Q.1. Biotin ligand binds to the protein Avidin with a dissociation constant value of 1 X 10-15 whereas the insulin binds to the insulin receptor protein with an association constant of 1 X 1010. Which one of the two has a greater affinity toward their respective protein? Explain. * Protein Avidin has a higher affinity for ligand biotin; kd has a reverse relationship with affinity . The lower Kd indicates that protein avidin will be half-saturated with bound ligand biotin at a much lower concentration of biotin than will insulin receptor.

Q.3. (6 Points) Explain the following:
a. Protoporphyrin ring and porphyrin ring

* In myoglobin, the heme consists of an organic part and an iron part. The organic part, protoporphyrin, is made up of four pyrrole rings linked by methene bridges to form a tetrapyrrole ring. The iron atom in the heme binds to four nitrogen atoms