4. The figure below shows ATP in the binding site of pyruvate kinase, an important enzyme incellular respiration. Note that only amino acids involved in interactions in the binding site areshown.LysHisATPNH; afafaforOH OHqatGluTyrAspa. What is the most likely chemical interaction occurring between the tyrosine and theribose of ATP?b. List one mutation to the lysine (Lys) in the binding site that would likely result in thekinase NOT being able to bind ATP (state the change in amino acid, not in the DNA ormRNA). In one sentence, explain why this mutation would likely lead to this change. Beas specific as possible.

Cellular respiration is a collection of three metabolic pathways that generate ATP by the oxidation…

Answered: 4. The figure below shows ATP in the…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter27: Metabolic Integration And Organ Specialization

Section: Chapter Questions

Problem 5P

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.Intramitochondrial ATP concentrations are about 5 mM, and phosphate con- centration is about 10 mM. If ADP is five times more abundant than AMP, calculate the molar concentrations of ADP and AMP at an energy charge of 0.85. Calculate AG for ATP hydrolysis at 37 °C under these conditions. The energy charge is the concentration of ATP plus half the concentration of ADP divided by the total adenine nucleotide concentration: [ATP] + 1/2[ADP] [ATP] + [ADP] + [AMP]
The interconverison of DHAP and GAP greatly favors the formation of DHAP at equilibirum. Yet the conversion of DHAP by triose phosphate isomerase proceeds readily. Why?
4. a. Calculate the KM (Michaelis constant) and the vmax (the maximum initial rate) for both substrates (sphingosine and ATP). Show your work, and be careful about units. b. threo-dihydrosphingosine, a stereoisomer of sphingosine, is an inhibitor of sphingosine kinase. What kind of inhibitor (competitive, uncompetitive, noncompetitive) is threo-dihydrosphingosine? Citing information from the Lineweaver-Burke plots, explain how you can tell.
. The allosterically regulated enzyme ATCase binds aspartic acid as a substrate and acylates the a-amino group. Succinate acts as a competitive inhibitor of ATCase because it binds the active site but can't be acylated. The dependence of vo on [aspartic acid] for ATCase is shown in panel (a) of the accompanying figure. Panel (b) shows the effect of increasing [succinate] on v, when [Asp] is held at a low concentration (see thick vertical arrow in panel (a)). Note that in panel (b), vo is not zero when [succinate] =0 (see thin horizontal arrow). Explain the shape of the curve in panel (b). Why does v, increase initially, before decreasing at higher [succinate]? Co0- COO CH2 CH, HC -NH, CH, COO COO Asp Succinate [Asp) [Succinate] [Asp] in experiment b (a) (b)
1. Protein tyrosine phosphatase enzymes are important regula- tory enzymes. Clinical trials show that inhibitors of these en- zymes can be important means for treating certain diseases, e.g., diabetes. Phosphatase enzymes catalyze removal of the phos- phoryl group from tyrosine residues of specific proteins convert- ing the phosphoryl group, i.e., PO3²-, into a phosphate through hydrolysis. As an example of a phosphatase enzyme, below are data collected to characterize protein tyrosine phosphatase-1B (PTP1B), an important enzyme regulating part of the pathway for uptake of glucose into cells. The activity was measured in the presence and absence of vanadate (VO4³-), an inhibitor of the enzyme. An artificial substrate, fluores- cein diphosphate (FDP), shown on the right, was used in the experiments. Upon hydrolysis FDP forms the product fluorescein monophosphate (FMP) that absorbs light at 450 nm, allowing activity to be measured spectrophotometrically. The results are provided in the…
16. The overall reaction for the glycolysis reaction is C6H₁2O6(aq) + 2NAD+ (aq) + 2ADP³(aq) + 2HPO(aq) + 2H₂O(1) 2CH3COCO₂ (aq) + 2NADH(aq) + 2ATP4 (aq) + 2H3O+ (aq). What is A,G at chemical equilibrium?
a. Protein X can be phosphorylated. Why would the phosphorylated form of protein X elute AFTER the unphosphorylated form from an ANION exchange column? Please describe in terms of: The chemical properties of phosphorylation modification b. The chemical properties of an anion exchange column and how it works c. Why is an inhibitor that mimics the transition state more effective at enzyme inhibition than an inhibitor that mimics the substrate? d. Protein X can be covalently modified with many methyl groups. What two general properties would be different between the unmethylated protein versus the methylated protein?
Creatine is a popular dietary supplement. What is the biochemical rationale for the use of creatine? It would serve as an electron donor to support reductive biosyntheses required to sustain cellular function. It would promote the movement of ions through ion channels and thus power the synthesis of ATP during exercise. It would be converted into creatine phosphate and thus serve as a rapid means of replenishing ATP during muscle contraction. O It would directly serve as an electron carrier to support the oxidation of fuel molecules and thus energy production. What type of exercise would benefit most from creatine supplementation? O a long-distance run a leisurely walk yoga O sprinting
4. (a) courses (such as this one) that NADH produced through glycoly- °H °H! sis in the cytosol can be used to generate ATP in the mitochon- dria. Yet, if 7-(14C)-NADH (in which the nicotinamide C-7 position is radioactively labeled; see diagram on the right) is added to rat hepatocytes, no radioactivity appears in the mitochondrial matrix while, if 4-(H)-NADH is added to hepatocytes, the tritium label soon appears in the mitochondrial matrix. Explain. It is generally stated and taught in biochemistry H H `NH2 NH2 R R [4-°H]NADH [7-14C]NADH
The enzyme mutase which is important for the synthetic of tyrosine and phenylalanine in saccharomyces cerevisiae has been studied as an example of an allosteric enzyme. Tyrosine acts as a negative effector for this enzyme. What effects would you see on the action of the enzyme were you to increase the concentration of tyrosine? The chorismate mutase would shift to its R conformation The curve showing the kinetics or chorismate mutase would shift to the right The curve showing the kinetics of chorismate mutase would shift to the left The chorismate mutase would become saturated more rapidly
3. Aspartate aminotransferase (AspAT) catalyzes the following reaction: COO™ C=O CH₂ COO Oxaloacetate The AspAT enzyme has two active-site arginines, Arg 386 and Arg 292, that interact with the a- carboxylate and ß-carboxylate groups on the aspartate substrate, respectively. Investigators stud- ied the mechanism of AspAT in more detail by constructing mutant AspAT enzymes in which either or both of the essential arginines were replaced with a lysine residue. The kinetic parame- ters for the wild-type enzyme and nutant enzymes are shown in the table. NH—CH-COO T CH₂ COO™ Aspartate α-Amino acid Enzyme 1. Wild-type Asp AT(Arg 292 Arg 386) 2. Mutant Asp AT(Lys 292 Arg 386) 3. Mutant Asp AT(Arg 292 Lys 386) 4. Mutant Asp AT(Lys 292 Lys 386) Asp-AT a-Keto acid KM (MM) 4 326 72 300 Kcat (S-1) 530 4.5 9.6 0.055 (a) The Michaelis constant is strictly not equivalent to an equilibrium binding constant; however under certain conditions the Michaelis constant does approach the equilibrium (dissoci-…
A point mutation in Hb diminishes hydrophobicity at the heme. Which of the following impacts would you predict? . Increased oxidation of Fe2+ and loss of O2 binding b. Decreased negative charges needed at the dimer/dimer interface to stabilize the T-state c. Decreased positive charges needed at the dimer/dimer interface to stabilize the T-state d. Shift the O2 binding curve of Hb to the left e. Decreased affinity for BPG in the T-state

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