Exam 2-2005Key

Exam 2-2005Key - BIO 361 EXAM 2 FALL 2005 NAME:_KEY_ ID:_...

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BIO 361 EXAM 2 FALL 2005 NAME:_______________KEY ______________________________ ID:_____________________________________________________ 1. Write Your name and ID on all pages 2. Write all answers in pen only 3. Limit your answers to the space provided 4. Make sure your exam has nine pages including this cover page Page 2 _______________ Page 3 _______________ Page 4 _______________ Page 5 _______________ Page 6 _______________ Page 7 _______________ Page 8 _______________ Page 9 _______________ Total _______________ Maximum of 100 points
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NAME:_____KEY ________________ ID:_________________________ 2 1. Name five mechanisms used to regulate enzyme activity other than allostery. (5 points) Feedback inhibition / Covalent modification (Phosphorylation or Ubiquitination) / Limited proteolysis / Iso(en)zymes / Protein degradation / Protein synthesis 2. Name the lipid shown below and identify all of its building blocks by circling the corresponding atoms and writing down the name. (6 points) Overall name: Phosphatidylcholine Stearate (Octadecanoate) Glycerol Phosphate Choline Arachidonate (All-cis- Δ 5 , Δ 8 , Δ 11 , Δ 14 -eicosotetraenoate) 3. The following kinetic parameters in the absence and presence of an inhibitor at a concentration of 10 nM were determined for an enzyme obeying Michaelis-Menten kinetics. No inhibitor: K M = 10 μ M V max = 22 μ M/s With inhibitor: K M = 10 μ M V max = 2 μ M/s (a) What type of inhibitor is this? Explain in no more than two sentences. (5 points) (b) Calculate the dissociation constant of the enzyme-inhibitor complex. (4 points) (a) This is a non-competitive inhibitor since K M is unchanged. (b) You determine α by dividing the reciprocal of the V max with inhibitor by the reciprocal of the V max without inhibitor: α =(1/2 μ M/s) / (1/22 μ M/s) = 11 From α = 1 + [I]/K i you get K i = 1 nM
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NAME:_____KEY ________________ ID:_________________________ 3 4. Answer the following questions in no more than two sentences each. (15 points) (a) What is the effect of 2,3-bisphosphoglycerate binding on hemoglobin? 2,3-Bisphosphoglycerate binds to the T-state of hemoglobin, thus shifting the T<->R equilibrium towards the T-state and hence lowering the oxygen affinity. (b) What aspect of enzyme catalysis do catalytic antibodies exploit? The preferential binding of the transition state by an enzyme (transition state stabilization). (c) What is the fundamental difference between serine/cysteine proteases on one hand and metalloproteases/aspartyl proteases on the other hand? While serine/cysteine proteases use a side chain (Ser or Cys) as the nucleophile attacking the carbonyl bond, metalloproteases/aspartyl proteases activate a water molecule to carry out the attack. (d)
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This note was uploaded on 11/19/2010 for the course BIO 361 taught by Professor Lake during the Fall '08 term at SUNY Stony Brook.

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Exam 2-2005Key - BIO 361 EXAM 2 FALL 2005 NAME:_KEY_ ID:_...

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