The rate constants of an enzyme-catalyzed reaction, obeying the Michaelis-Mentenkinetics, have been determined :E + SK₁ = 2 x 108 M-¹ S-¹-1-1-1K-₁= 1 x 10³ SK₂ = 5 x 10³ S-1K₁1K-1ESK₂E +P1- Determine the Michaelis constant Km of the enzyme.2- Determine the catalytic constant (kcat) of the enzyme.3- Determine the catalytic efficiency of the enzyme.

The enzyme interacts with the substrate by attaching to its active site to produce the…

Answered: The rate constants of an…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter25: Nitrogen Acquisition And Amino Acid Metabolism

Section: Chapter Questions

Problem 22P

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The protein catalase catalyzes the reaction 2H,O,(aq) — 2H,O(l) + O,(g) and has a Michaelis-Menten constant of KM = 25 mM and a turnover number of 4.0 × 107 s¯¹. The total enzyme concentration is 0.010 µM and the initial substrate concentration is 4.83 µM. Catalase has a single active site. Calculate the value of Rmax (often written as Vmax) for this enzyme. Rmax Calculate the initial rate, R (often written as V), of this reaction. R = ×10 mM.s-1 mM-s-1
You are working on an enzyme that obeys standard Michaelis-Menten kinetics. Based on the following reaction expression, what is the Km value for this enzyme? E+SESE + P . . . k₁ = 880.8 M-¹5-1 k.₁ = 42.18 S-1 k₂ = 56.29 S-1
The initial rates of an enzyme-catalyzed reaction have been determined for five different [S] (see table below). [S]o (mol.L-¹) 1.0 x 10 1.5 x 10-4 2.0 x 10-4 -4 5.0 x 10 7.5 x 10-4 -1 Vo (μmol.L-¹ min-¹) 28 35 42 63 75 1- Determine graphically the value of Km (first with the Michaelis-Menten representation and then with the Lineweaver-Burk representation, then compare by reporting on the Michaelis-Menten representation the values found by the Lineweaver-Burk representation) 2- Calculate the concentration of a competitive inhibitor 1, with a K₁ value of 2.4.104 M, whose action would quadruple the apparent value of Km.
Assume that an enzyme-catalyzed reaction follows the scheme shown: E + S ES E + P k₁ = 1 x 10%/M-s k-1 = 2.5 x 10%/s k2= 3.4 x 107s What is the dissociation constant for the enzyme-substrate, Ks? What is the Michaelis constant, Km, for this enzyme? What is the turnover number, Kcat, for this enzyme? What is the catalytic efficiency for the enzyme? If the initial Et concentration is 0.25mM, what is Vmax?
A particular enzyme-catalyzed reaction has an apparent Vmax = 9.00 nmol s-1 and α' = 3.00 when 2.00 µmol L-1 inhibitor X is present and uncompetitively inhibiting the reaction. Calculate Vmax for the uninhibited reaction in nmol s-1.
The KMof the enzyme for the substrate adenosine is 3 × 10ꟷ5M. The product inosine acts as an inhibitor of the reaction, with an inhibition constant (KI, the dissociation constant for enzyme-inhibitor binding) of 3 × 10ꟷ4M. However, a transition state analog,Inhibits the reaction with KIof 1.5 × 10ꟷ13M. Explain why 1,6-dihydroinosine serves as a better inhibitor of adenosine deaminase than inosine. Elaborate on your answe
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41 The following data describe an enzyme-catalyzed reaction (hydrolysis of carbobenzoxyglycyl-L-tryptophan) Plot these results using the Lineweaver-Burk method, and determine values for KM and Vmax Velocity (mM.sec-) 0 024 0 036 0 053 0 060 0 061 0 062 Substrate Concentration (mM) 25 50 10 0 15 0 200 25 0 42 If the KM of an enzyme for its substrate remains constant as the concentration of the inhibitor increases, what can be said about the mode of inhibition and why? 43 Calculate the turnover number for an enzyme, assumıng Vmax IS 05 M sec1 and the concentration of the enzyme used is 0 002 M Why is it useful to know this? 44 Dıscuss the mechanism of the Bohr effect that occurs during the interactions of Hb with oxygen under physiological conditions in the lungs and tissues Make use of relevant graphs and diagrams to explain your answer
#1 Specify the role each of the following amino acids play within the crystal structure and/or active site for Be as specific as possible, with pictures (and mechanistic arrows) as necessary. His11 Arg140 Glu89 Trp68 #2 Provide a step-wise mechanism for the reaction Bisphosphoglycerate mutase catalyzes, using the amino acids responsible for aiding in catalysis. You do not need to add surrounding amino acids that aid in substrate specificity. (drawn out)
Enzyme X can be inhibited by two distinct inhibitors, only one of which is acting as a competitive inhibitor, while the other one is non-competitive. The three plots below (designated A, B, and Cy show Michaelis-Menten kinetics for the reactions carried out with the same concentr ation of the enzyme and either in the absence of any inhibitors or in the presence of one of the two inhibitors. Match the type of reaction (uninhibited, competitive inhibition, non-competitive inhibition) with the corresponding plot? Plot A Plot B Plot C Substrate concentration 1.Plot A v LUninhibited roaction 2. Plot C v Inhibition by a competitive inhibitor 3Plot B v Inhibition by a non-competitive inhibitor A Moving to another question will save this response. lup
a) Determine kcat (in units of sec-1) for a particular enzyme, given the following information: Vo = 144 mmol/min; [S] = 2 mM; Km = 0.5 mM; Enzyme Molecular weight = 40,000 mg/mmole; 8 mg of enzyme used in assay generating this data. b) In general, explain how the total enzyme concentration affects turnover number and Vmax?
An enzyme has a V of 1.2 uM s The Km for its substrate is 10 µM. max Calculate the initial reaction velocity, Vo, for each substrate concentration, [S]. Calculate Vo when [S] is 2 µM. Vo = µM s Calculate Vo when [S] is 10 µM. Vo = µM s-1 Calculate Vo when [S] is 30 µM. Vo = µM s-1

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