The glutamate dehydrogenase (GDH) catalyses the following reaction:+H₂N-H--CH₂-CH₂COOacide glutamiqueCOO™®+ NAD+ + H₂OGDHCOOC:CH₂CH₂COO™O+ NH4+ NADH + H*The activity of GDH is monitored in the sense of the formation of glutamate using thefollowing conditions:-0.2 mL of 5 M ammonium sulphate2.4 mL of buffer at pH 80.1 mL of NADH at 6.15 mg.mL-¹ (M = 709 g.mol-¹)0.2 mL of 1 M a-ketoglutarate solutionWarm mixture at 25 °C for 5 min- Add 0.1 mL of GDH solution containing 1.6 mg.mL-¹protein to start thereaction.acide a-cétoglutariqueThe change in absorbance at 340 nm is monitored, in a 1-cm cuvette, every minutefor 10 min. Results are given in the table below:Data: ENADH at 340 nm = 6220 M¹.cm¹Time (min) 1 2 3 4 5 6 7 8 91.760 1.718 1.675 1.635 1.595 1.550 1.510 1.489 1.476A340101.451- Draw the graph A = f(t). Calculate A340 at t = 0 and place this point on the curve.- Comment the shape of the curve, particularly the portion that corresponds to aplateau.

Enzymes are biocatalysts. The rate of the enzyme catalyzed reaction can be measured in 2 ways:…

Answered: The glutamate dehydrogenase (GDH)…

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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During Krebs cycle, the conversion of isocitrate to alpha-keto glutarate involves all of the following reactions/mechanisms except Reduction of isocitrate Reduction of NAD+ Decarboxylation of isocitrate Oxidation of isocitrate
Which of the following regulatory mechanisms are used to regulate the enzyme activity of the pyruvate dehydrogenase complex (PDH)? 1) its activity is decreased by elevated levels of the products of the reaction via allosteric control 2) its activity can be modulated only through reversible covalent modification (phosphorylation/dephosphorylation) 3) insulin causes the complex to be phosphorylated, thus increases its activity 4) the complex is more active when dephosphorylated, a process triggered by insulin 5) the protein kinase that phosphorylates the PDH complex is sensitive to changes in the levels of ATP a) 2+3+5 b) 1+2+3 c) 1+3+5 d) 2+4+5
Which of the following catalyzes a step that does NOT produce CO2? Group of answer choices alpha-ketoglutarate dehydrogenase complex malate dehydrogenase pyruvate dehydrogenase complex isocitrate dehydrogenase Citrate synthase is regulated by... Group of answer choices Concentrations of substrate and products Fructose-2,6-Bisphosphate Covalent modification Allosteric regulation by the levels of NADDH
One consequence of ethanol addiction is fatty liver disease, an illness in which liver cells accumulate large amounts of triacylglycerols, the esters derived from glycerol and fatty acids. Ethanol is oxidized in the cytoplasm of liver cells by alcohol dehydrogenase and aldehyde dehydrogenase to yield acetate and 2 NADH. Acetate is then transported into the mitochondrion, where it is converted to acetyl-CoA and metabolized in the citric acid cycle. When alcohol is consumed in excessive quantities, the resulting high levels of NADH cause metabolic abnormalities, one of which is high levels of fatty acid synthesis. Fatty acid synthesis, also a cytoplasmic process, uses acetyl-CoA as a substrate and NADPH as a reducing agent. Speculate about how a high level of cytoplasmic NADH provides a source of NADPH for fatty acid synthesis.
One of the consequences of ethanol addiction is fattyliver disease, an illness in which liver cells accumulatetriacylglycerols, the esters derived from glycerol and fattyacids. Ethanol is oxidized in the cytoplasm of liver cells byalcohol dehydrogenase and aldehyde dehydrogenase to yieldacetate and 2 NADH. Acetate is then transported into themitochondrion, where it is converted to acetyl-CoA andmetabolized by the citric acid cycle. When alcohol is consumed in excessive quantities, the resulting high levels ofNADH cause metabolic abnormalities, one of which is highlevels of fatty acid synthesis. Fatty acid synthesis, also acytoplasmic process, uses acetyl-CoA as a substrate andNADPH as a reducing agent. Determine how a high level ofcytoplasmic NADH provides a source of NADPH for fattyacid synthesis.
phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate and represents the key control point in mammalian glycolysis. The enzyme is a homotetramer that is inhibited by ATP binding, activated by AMP binding, negatively regulated by phosphorylation, and competitively inhibited by 2,5-anhydro-D-glucitol-1,6-diphosphate. (a) Would you expect a plot of the initial rate of fructose 1,6-bisphosphate formation as a function of substrate concentration to show a sigmoidal or hyperbolic curve? (b) How would each of the regulators above affect the dynamics of the T state to R state equilibrium of phosphofructokinase? Briefly explain your reasoning. (c) If it were possible to isolate phosphofructokinase monomers in an active form, how would you expect the kinetics in (a) to be affected? How would the rate of the reaction be affected by ATP, AMP, and 2,5-anhydro-D-glucitol-1,6-diphosphate? Briefly explain your answers.
The steps of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involve all of the following except: a. ATP synthesis. b. catalysis by phosphoglycerate kinase. c. oxidation of NADH to NAD+. d. the formation of 1,3-bisphosphoglycerate. e. utilization of Pi.
What is the overall net reaction for the Pyruvate Dehydrogenase Complex? What enzyme(s) in the Citric Acid Cyclecatalyze(s) substrate-level phosphorylation? What enzyme(s) in the Citric Acid Cyclecatalyze(s) decarboxylation reactions? What enzyme(s) of the Citric Acid Cyclecatalyze(s) reactions in which NAD+or FAD is reduced to NADH or FADH2, respectively?
Select the following enzymes that utilize a mechanism where ATP serves as the phosphate donor. Select ALL that apply: a) glyceraldehyde 3 phosphate dehydrogenase b) hexokinase c) aldolase class 1 d) PFK e) phosphoglucoisomerase
If α-ketoglutarate is removed from TCA cycle and used to make glutamate, how many of each of the cofactors (not intermediates) and high energy molecules in the TCA cycle are lost? How much ATP does this equate to (NADH = 2.5 ATP, FADH2 = 1.5 ATP)?
The malaria parasite Plasmodium falciparum does not carry out oxidative phosphorylation and therefore does not use the citric acid cycle to generate reduced cofactors. Instead, the parasite converts amino acid–derived α ketoglutarate to succinate. Write an equation for the α-ketoglutarate → succinate conversion that follows (a) the oxidative (clockwise) path of the citric acid cycle or (b) the reductive (counterclockwise) path of the cycle.
For the following enzymes (3-6) predict how the conditions will most likely affect the enzymes activity with one of the following and provide a 1 sentence explanation: a. increase activity b. decrease activity c. not likely to alter activity 3) alpha-ketoglutarate dehydrogenase complex binding to AMP when [AMP] is high. 4) phosphohexose isomerase binding NADH when [NADH] is high 5) phosphofructose-1 binding NAD+ when [NAD+] is high 6) pyruvate dehydrogenase complex binding to ATP when [ATP] is high

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