PracticeExam3_key - Name_KEY_ EID_ CH n339K Exam 3 26 June...

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Name______________ KEY ___________________________________ EID__________________________________________ 1 CH n339K Exam 3 26 June 2008 125 points total 10 pts. 1 . a. Which set of binding data is likely to represent cooperative ligand binding to an oligomeric protein? A. [Ligand] (mM) θ 0.1 0.3 0.2 0.5 0.4 0.7 0.7 0.9 B. [Ligand] (mM) θ 0.2 0.1 0.3 0.3 0.4 0.6 0.6 0.8 B - the data in Table B plot a sigmoidal curve, characteristic of cooperativity, whereas the data in Table A plot a hyperbola (see graph) 10 pts. b. Estimate the K d from the data in Table A. K d is the ligand concentration at which half the available binding sites are occupied (i.e. θ = 0.5)(see Fig. 5-4a, p. 156). From the Table A, K d = 0.2 mM (see graph). 2 . In published experiments ( JBC 262 :12700-12713, 1987), hemoglobin was carboxymethylated in vitro at the NH 2 - terminal of the α -subunits and/or the β -subunits. This covalent modification (Hb•NHCH 2 COO - ) yields hemoglobin derivatives that should be stable analogues of the corresponding carbamino adducts (Hb•NHCOO - ) that form upon reaction of hemoglobin with CO 2 in vivo (see p. 166). X-ray crystal studies show that the carboxymethylated hemoglobins do indeed have the same structure as native hemoglobin containing carbamino adducts. In answering the following, be sure to justify your predictions based on your understanding of hemoglobin structure and function (for each part, you get 4 pts for your prediction and 6 pts for your justification). Carboxymethylated Hb serves as a very good analogue of carbamino Hb, as evidenced by very similar X-ray
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This note was uploaded on 11/25/2009 for the course CH 53890 taught by Professor Raymonds during the Spring '09 term at University of Texas at Austin.

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PracticeExam3_key - Name_KEY_ EID_ CH n339K Exam 3 26 June...

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