Velocity, activity units/mg protein 51 3 2 0 5 15 20 Aspartate concentration, mM - 10 Control With With CTP With ATP CTP 25 Figure 2: Kinetics of ATCase in the presence of ATP and CTP (based on Gerhart and Pardee, 1962). The kinetics of the ATCase reaction were examined using increasing concentrations of aspartate, in the presence and absence of CTP and ATP as shown in Figure 2. a. What information can you obtain by looking at the shapes of the curves in this figure? b. What kinetic parameter(s) change in the presence of CTP? What parameter(s) do not change? What is the significance of these observations? c. Answer question 2b for ATP.

Velocity, activity units/mg protein 51 3 2 0 5 15 20 Aspartate concentration, mM - 10 Control With With CTP With ATP CTP 25 Figure 2: Kinetics of ATCase in the presence of ATP and CTP (based on Gerhart and Pardee, 1962). The kinetics of the ATCase reaction were examined using increasing concentrations of aspartate, in the presence and absence of CTP and ATP as shown in Figure 2. a. What information can you obtain by looking at the shapes of the curves in this figure? b. What kinetic parameter(s) change in the presence of CTP? What parameter(s) do not change? What is the significance of these observations? c. Answer question 2b for ATP.

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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Based on the Lineweaver-Burke plot attached. Kinetic data were generated in the (1) absence of any inhibitor, (2) presence of 15 µM of a reversible inhibitor, or (3) presence of 20 µM of a second (distinct) reversible inhibitor. Purified enzyme concentration was 5 µM. The y-intercept of Lines (A) and (B) is 0.9 sec/uM; the y-intercept of Line (C) is 0.3 sec/uM. The slope of Line (A) is 1.8 sec; the slope of Lines (B) and (C) is 0.6 sec. QUESTION: Line (A) represents ____________. A. an enzyme-catalyzed reaction in the absence of any inhibitor. B. an enzyme-catalyzed reaction in the presence of a competitive inhibitor. C. an enzyme-catalyzed reaction in the presence of an uncompetitive inhibitor. D. an enzyme-catalyzed reaction in the presence of a noncompetitive, or mixed, inhibitor.
enzyme-inhibitor complex requires 450 kJ.mol-1 to dissociate and that it displays kinetics somehow similar to non-competitive inhibition, does this is inhibitor good to use to inhibit toxanthine oxidase in the case of hyperuricemia and gout?
Kinetic Parameters of Enzyme-Catalyzed Reactions TABLE 12-1 The Values of KM, Keat, and Keat/KM for Some Enzymes and Substrates Enzyme Substrate KM (M) 9.5 x 10-5 1.2 x 10-² 2.6 x 10-2 2.5 x 10-2 4.4 x 10-1 8.8 x 10-2 6.6 x 10-4 Acetylcholinesterase Carbonic anhydrase Catalase Chymotrypsin Fumarase Urease Acetylcholine CO₂ HCO₁ H₂O₂ N-Acetylglycine ethyl ester N-Acetylvaline ethyl ester N-Acetyltyrosine ethyl ester Fumarate Malate Urea 5.0 x 10-6 2.5 x 10-5 2.5 x 10-2 Keat (S-¹) 1.4 x 104 1.0 × 106 4.0 × 105 1.0 X 107 5.1 x 10-2 1.7 × 10-1 1.9 X 10² 8.0 x 10² 9.0 × 10² 1.0 X 104 Keat/KM (M¹s¹) 1.5 × 108 8.3 x 107 1.5 x 107 4.0 X 108 1.2 x 10-1 1.9 2.9 × 105 1.6 × 108 3.6 X 107 4.0 X 105 Which enzyme is the most catalytically efficient? Which substrate does chymotrypsin bind to most tightly (assume k_₁ >> K₂)? Is fumarate or malate a better substrate of fumarase? Is it possible to have a kcat/KM of greater than 1 x 10⁹ M-¹ s-¹? Why or why not?
KINETIC CONSTANT No Na2HPO4 25mM Na2HPO4 50mM Na2HPO4 Vmax nmol p-NP. Min- 20.3252 14.30615 17.30104 Km mM -0.819106 -0.46495 -0.352941 1. What does this suggest about the structure of the active side of the enzyme?
Km value should be more than 10% apart, use non-competitive inhibitor
Select the incorrect statement. With regards to free energy ΔG of the reaction below E+S ⇌ ES Negative ΔG mean the reaction toward is facourable More negative value of ΔG indicates stronger binding to S to E It is possible to compute disassociation constant from the ΔG value alone It is possible to calculate the term ( ΔH – T ΔS) from the value of ΔGalone ΔG = 0 indicates (ES)/(E)(S) =1 None of the above
2.1 ANSWER THE TABLE
2.3
Please answer asap and in short
ATP Counting
Many years later, in 1989, Wild, et al. revisited the idea of allosteric control of ATCase by CTP. They noted that CTP did indeed inhibit ATCase, but that the inhibition was always incomplete, even at high concentrations of CTP. They hypothesized that perhaps CTP did not act alone, but in combination with some other nucleotide. They tested the activity of ATCase in the presence of several nucleotide combinations. The results are shown in Table 3. a. What combination gives the most effective inhibition? b. What is the physiological significance of this combination? c. Revise Figure 1 to include this new information. d. Redraw Figure 2 to include this new information. How does the combination compare with the values for the nucleotides alone? Table 3: Relative specific activities for combinations of nucleotide effectors. A value greater than one indicates stimulation, a value less than one indicates inhibition. Nucleotide Effector ATP CTP GTP UTP ATP/CTP ATP/GTP ATP/UTP CTP/GTP CTP/UTP…
Part 1: Assess the following partial results section below by editing it for brevity by omitting any unnecessary parts (1 point), explain why you decided to remove certain sections (1 point): To evaluate inhibitory effects of the selected molecules, 10mM stock solutions of each molecule were prepared in DMSO. A reaction mixture (200μl) was prepared with the same formula optimized for the enzyme activity assay (0.1 M Tris-HCl ph 8, 0.1 M KCI, 25 mM NaCl, 0.25 mM ATP, and two units of inorganic yeast pyrophosphatase) with 10 µM of the sample molecule. The reaction mixture was incubated for 20 minutes at ambient temperature. Enzymatic reaction was triggered by addition of the substrate B (0.2 mM) and the absorbance of the product was monitored at 290 nm for 10 minutes. Six out of 15 sample molecules showed appreciable inhibition at 10 μM (Figure 5). Three of the molecules, A3, A6, and A7 exhibited more than 50% inhibition of the enzyme activity and were further diluted to find the minimal…