Biochemistry Homework 2.docx - Biochemistry Homework Due – Wednesday September 25 Groups – Same as for Homework#1 1 Hemoglobin differs from

Biochemistry Homework 2.docx - Biochemistry Homework Due...

This preview shows page 1 - 3 out of 4 pages.

Biochemistry Homework Due – Wednesday, September 25 Groups – Same as for Homework #1 1. Hemoglobin differs from myoglobin in that it has four binding sites for oxygen (compared to myoglobin’s single binding site) and is cooperative. Are all molecules with multiple binding sites cooperative? Explain. Answer: No, because a molecule is only cooperative if it is allosteric. And a molecule is only allosteric if it meets the following 3 structural features: 1) 2 or more subunit smaller functioning unit of the whole, 2) 2 or more ligand molecules must bind, and 3) when ligand binds to one subunit, the subunit interacts with other subunit that cause conformational change. 2. How does the structure of myoglobin help to prevent bound oxygen from being released as superoxide (O 2 - )? Answer: Myoglobin prevents the bound oxygen from becoming a superoxide anion through an additional histidine amino acid. The histidine is located within the binding pocket of myoglobin donating a hydrogen bond to the bound oxygen molecule. This reduces the likelihood that superoxide is released. 3. Hemoglobin is a tetrameric protein consisting of two α and two b polypeptide subunits. The structures of the α and b subunits are remarkable similar to that of myoglobin. However, at a number of positions, hydrophilic residues in myoglobin have been replaced by hydrophobic residues in hemoglobin. a. How can this observation be reconciled with the generalization that hydrophobic residues fold into the interior of proteins? Answer: Mb is only one subunit, with hydrophilic residues on the outside surface. Hb is composed of four subunits, so there is an area between these subunits that is the core. This is hydrophobic, thus, these residues that were on the outside of Mb are now folded on the inside of Hb due to its structure. b. In this regard, what can you say about the nature of the interactions that determine the quaternary structure of hemoglobin? Answer: Hydrophobic forces play an important role in the maintenance of the quaternary structure. 4. Several oxygen dissociation curves are shown in Figure 7.1. Assuming that curve 3 corresponds to isolated hemoglobin placed in a solution containing physiologic concentrations
Image of page 1

Subscribe to view the full document.

of CO 2 and BPG at a pH of 7.0, indicate which of the curves reflects the following changes in conditions: a. decreased CO 2 concentration
Image of page 2
Image of page 3
  • Spring '14
  • DevinS.Iimoto

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask bonus questions You can ask questions ( expire soon) You can ask questions (will expire )
Answers in as fast as 15 minutes