2. (Labeling molecules with isotopes has long been used to trace andcharacterize metabolic pathways. Upon oxidation in the mammalian liver of L-glutamate labeled as shown on the right, write the metabolic reactions thatlead to the products as shown below using structure formulas. No need toinclude the enzymes.(a)succinate [ (1-14C)-succinate ](b)(c)(d)citrulline [ 15NH2-CO-NH-(CH2)3-CH (NH3)-COO-]H COO-15,1 + 14 [H-NC-Hurea [ 15NH₂-CO-15NH₂]aspartate [ (1-14C,2-15N)-L-aspartate and (4-¹4C,2-¹5N)-L- aspartate ]H CH₂LCH₂COO-(2-14C, 15N)-L-glutamate

Answered: Image /qna-images/answer/38280c8d-204a-496f-8e5b-943f621d4c98.jpg

Answered: 2. ( Labeling molecules with isotopes…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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3 Compound A is an optically active mixed triglyceride, for which the following apply: a) contains three different fatty acids and has molecular formula C55H10406. b) by catalytic hydrogenation it is converted into a new triglyceride, B, which is not optically active. c) the transesterification of B under the influence of methanol in an acidic environment gives three products (C, D and glycerol) of which C has a total of 21 carbon atoms. Determine the two possible structures of A and the structures of B, C and D.
12. Nirogenase is an enzyme that converts the remarkably stable triple bond in N2 into a usable form. It uses an iron sulfur cluster comprised of iron and the sulfur atoms of several active site cysteine residues. Based on your knowledge of Biochemistry what is the enzyme doing to effectively carry out this reaction? a) stabilizing the transition state for the reaction by hydrophobic effects b) stabilizing the ground state for the reaction by hydrophobic effects c) stabilizing the transition state for the reaction by metal ion catalysis d) stabilizing the ground state for the reaction by metal ion catalysis e) all of the above
Stearidonic acid (C18H28O2) is an unsaturated fatty acid obtained from oils isolated from hemp and blackcurrant (see also Problem 10.11). a. What fatty acid is formed when stearidonic acid is hydrogenated with excess Hạ and a Pd catalyst? b. What fatty acids are formed when stearidonic acid is hydrogenated with one equivalent of Hz and a Pd catalyst? c. Draw the structure of a possible product formed when stearidonic acid is hydrogenated with one equivalent of H2 and a Pd catalyst, and one double OH stearidonic acid bond is isomerized to a trans isomer. d. How do the melting points of the following fatty acids compare: stearidonic acid; one of the products formed in part (b); the product drawn in part (c)?
7. Chalcone isomerase catalyzes the reaction illustrated below. A series of modification experiments were performed on this enzyme to identify which amino acid residues might be in the active site and which might promote the cyclization reaction. OH Ho. Но Explain the following results: A) Acetic anhydride treatment inhibited enzyme activity. B) Pyrocarbonate inhibited activity and was found to modify 7 residues. However, this enzyme only contains 6 His and modification of these did not affect activity. C) lodoacetate inhibited activity but this effect coult be decreased in the presence of substrate or product. D) Methane methanethiol sulfonate modified the enzyme but did not inhibit catalytic turnover. In addition, this modification was reversed in the presence of B-mercaptoethanol. keNyons Rengent
10. Procaine is known to undergo faster metabolic hydrolysis than procainamide. Give explanation. -NET2 -NEt2 HN H2N- H2N- Procainamide Procaine 11. In phase 2 metabolic transformation chloramphenicol the primary alcohol is converted to a glucuronide conjugate. Draw chemical structure of the product. Provide the name of enzyme that catalyze this metabolic reaction. он ? CHCI2 O2N- но
2) Briefly explain the relationships between [AMP], [ADP], and [F 2,6-BP] and [F-6-P] in the following graph (a). Fructose 6 – phosphate (F6P) → Fructose 1,6 – bisphosphate (FBP) AG = -22.2 kJ/mol 100 +0.13 mM fructose-2,6- bisphosphate 50 No fructose-2,6- bisphosphate [Fructose-6-phosphate] (a) Activation of PFK by fructose-2,6-bisphosphate. PFK activity Reaction rate, % Vmax
Using Figure 1.3 of the Introduction as an example, a) draw all the structures of the tribasic amino acid lysine involved in the equilibrium reactions that would take place during titration against NaOH, starting with the fully protonated form below (draw the R-group in full). HAN+-CH- COOH (CH2)4 NH°+ b) indicate the numerical pa value of each equilibrium reaction, and which ionizable group is being dissociated in each step. c) indicate the net charge of the amino acid at each step and identify the zwitterion. d) Calculate the pI of this amino acid (show the calculation). e) What would be the predominant ionization states of this amino acid at physiological pH (7.4) and at this pH, what would the ratio of these two states be (show the calculation)?
3. Prostaglandins (5) are derived from the 20-carbon fatty acid arachidonic acid in a reaction catalyzed by the enzyme prostaglandin endoperoxide synthase. This enzyme, a cyclooxygenase, uses oxygen to convert arachidonic acid () to PGG2 (G2), the immediate precursor of many different prostaglandins. a) The kinetic data given below are for the reaction catalyzed by prostaglandin endoperoxide synthase. Focusing here on the first two columns, determine the Vmax and Km of the enzyme (note, ¤¯↑¤Ð 的单位) [Arachidonic Rate of formation acid] of PGG₂ (MM) (mm/min) 0.5 1.0 1.5 2.5 3.5 23.5 32.2 36.9 41.8 44.0 Rate of formation of PGG₂ with 10 mg/mL ibuprofen (mm/min) 16.67 25.25 30.49 37.04 38.91 b) Ibuprofen () is an inhibitor of prostaglandin endoperoxide synthase. By inhibiting the synthesis of prostaglandins, ibuprofen reduces inflammation and pain. You have learned the three mechanisms() for enzyme inhibition, what they are and how Vmax and Km changed? (you can illustrate as a table) c)…
5. Consider the reaction for assembly of a tetrapeptide from for amino acids: Serine + Proline + Alanine + Methionine ----> SPAM tetrapeptide Is this reaction anabolic or catabolic? Is this a positive or negative delta G reaction? List at least three other terms you could use to describe this reaction. 6. Consider the reaction: Glutamic acid + Ammonia + ATP ----> Glutamate + ADP + Pi Is this reaction anabolic or catabolic? Is this a positive or negative delta G reaction? This is actually an example of a coupled reaction! Briefly, explain why reaction coupling is required, and how it works in this example.
1. Acid phosphatases are an important group of enzymes that can be detected in human blood serum, Under slightly acidic conditions (pH 5.0), this group of enzymes can hydrolyze biological phosphate esters as follows: R-0-P-03-2 + H 20 → R-OH + HO- P-03-2. Acid phosphatases are produced and can be detected in erythrocytes, kidney, spleen, the liver, and prostrate gland. The enzyme from the prostrate gland is clinically important because an increased activity in the blood is frequently an indication of can- cer of the prostrate gland. Tartrate ion can strongly inhibit the phosphatase from the prostrate gland, but not acid phosphatases from other tissues. How can you use the information above to develop a specific procedure for measuring the activity of the acid phosphatase of the prostrate gland in human blood serum?
5. For a Michaelis-Menten enzyme, k1 = 5.2 ⅹ 108 M-1 s-1, k-1 = 3.1 ⅹ 104 s-1, and k2 = 3.4 ⅹ 105 s-1. a) Write out the reaction, showing k1, k-1, and k2. Calculate Ks and Km. Does substrate binding approach equilibrium or the steady state? Justify your answer. b) What is kcat for this reaction? Justify your answer. c) Calculate Vmax for the enzyme. The total enzyme concentration is 25 pmol L-1, and each enzyme has two active sites. d) What substrate concentration would be required for the reaction in (c) to reach half of Vmax. Justify your answer mathematically. e) A second Michaelis-Menten enzyme has k1 = 4.2 ⅹ 107 M-1 s-1, k-1 = 6.1 ⅹ 104 s-1, and k2 = 5.3 ⅹ 102 s-1. Which enzyme is most efficient? 6. A pharmaceutical company is trying to develop a
(b) The values of kinetic parameters for a variety of synthetic ester and peptide substrates ofa- chymotrypsin are compared for the reaction scheme below where ES is the Michaelis complex, ES' E+S Substrate K₁ N-Ac-Trp–OC₂H5 N-Ac-Phe-OC2H5 N-Ac-Leu-OC2H5 N-Ac-Phe-CONH2 N-Ac-Tyr-p-nitro-anilide ES K₂ 3.5 13.0 3.2 1.7 K-₁ is the acylenzyme, P₁ is the first product to be released, P2 is the second product, k2 is the acylation rate constant, k3 is the deacylation rate constant, and kcat = k2 k3/( k2 + k³). In the table below, N- Ac = N-acetyl; -CONH₂ = carboxamide; -OC₂H5 = ethyl ester; p-nitroanilide = −NH-C6H4-NO2 simulating a peptide group. ES' K2 (S-¹) K3 (S-1) 0.84 2.2 0.19 P₁ K3 0.073 H → E+ P2 Kcat (S-1) 0.82 1.9 0.18 0.070 0.038 KM (MM) 0.08 1.3 4.2 24.0 0.35 1 Kcat/ KM (mM-¹ s¯¹) 10.3 1.5 0.04 0.003 0.11 The value of kcat for N-Ac-Phe-OC2H5 is two-fold greater than that for the L-tryptophanyl analog and more than 10-fold greater than the value of kcat for the ester substrate…

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