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Exam_2_S08 - Short answer questions(20pts total 1 Draw the...

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Short answer questions (20pts total): 1) Draw the structure of the following peptide, showing the charges as they would exist at pH 7: (2pts) Gly-His-Arg-Pro 2) In some animals (for example fish) ATP plays the role that biphosphoglycerate does in human red blood cells. On the graph below draw oxygen binding curves of fish hemoglobin in the presence and absence of ATP. (2pts) Not the greatest graph as the lines should not cross! CH 2 C H N C H C H N H C C N C H C O - O O O O CH 2 N HN CH 2 CH 2 CH 2 NH C +H 2 N NH 2 CH 2 H 2 C H 2 C +H 3 N -ATP +ATP
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3) During the course of protein cleavage by the enzyme chymotrypsin, the C-Terminal fragment of the polypeptide substrate is released, while the remaining N-Terminal fragment is covalently bound to the enzyme. In the diagram below draw the structure of the covalent intermediate (4pts). 4) The basic equation to describe the enzymatic behavior of a simple enzyme catalyzed reaction as derived by Michaelis and Menton is: v 0 =V max [S] K m +[S] Use this equation to show that K m is equal to the substrate concentration, when the velocity (v 0 ) is equal to ½ V max . (3pts) For this problem the most direct approach is to simply use what you are told: K m = [S] so substitute v 0 =V max [S] [S]+[S] v 0 =V max [S] 2[S] Cancel the [S] v 0 =V max 2 Or v 0 =½V max CH 2 uni2015 O uni2015 C=O R H-Bond to His57
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5) Study the Michaelis-Menton graph velow and identify the curve that corresponds to each of the following reaction conditions (1.5pts) a) no inhibitor - 1 b) competitive inhibitior - 2 c) mixed or non-competitive inhibitor - 3 6) Muscle collagen contains very little cysteine but is stabilized by what type of cross- linking (structures not necessary): (1pt) Lysine - Lysine List three other ways in which the secondary structure of the muscle structural protein collagen differs from an alpha helix (1.5pts). a) Collagen is a triple helix of three proteins. α -helices are 2° structure in proteins. b) Collagen’s individual helices are left-handed helices; α -helices are right-handed. c) Collagen has a triple repeat w/ glycine, proline and ( α -helices absent) hypoxyproline. Also, Collagen has the glycine towards one side of the helix with the proline and hydroxyproline towards the other. α -helices amino acids are more varied. This makes a somewhat more rigid structure for collagen. Collagen helices’ angle & pitch are higher and steeper so they are looser and narrower.
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7) Using the supplied graph paper draw a Lineweaver-Burk plot to estimate the K m and V max of the enzyme Primaryase. Be sure to give the appropriate units. (5pts) [S] mM [v 0 ] mM/sec 0.25 0.75 0.5 1.20 1.0 1.71 2.0 2.18 -1/K M = -1/(1.33 mM -1 ) 1/V Max = 1/(0.33 s/mM) K M = 0.75 mM V Max = 3 mM/s
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Multiple Choice Questions. Use the scantron sheet to answer these questions. The following questions # 1- 24 are worth 1pt each Answer the following questions (#1-7) with the below answers (pick the best answer, the answers may be used more than once or not at all).
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