You run an experiment using 0.5 µM of an enzyme. The kinetic parameters for your enzyme are kcat =1800 s-1 and KM = 25 µM.(a) If k-1 is 240 s -1, what is the value of k1? (Report your answer in units of M-1 s -1)(b) What is Vmax for the enzyme (Don't forget to include units in your answer)?(c) You set up an experiment with the following initial concentrations of substrate. Calculate the rate ofthe reaction at each substrate concentration (report your answer in units of µM sec-1[S](μM)11001000[S][μM)11001000v (μMsec ¹)(d) You now add 10 nM of a competitive inhibitor with a KI = 2 nM. What is the rate of the reaction (v)for the following substrate concentrations and how does it compare to the rate without inhibitor (VO)?Vinhib (uMsec-¹)Vinhih/V

Turnover number (kcat) is the maximum number of substrate molecules that are converted to product…

Answered: You run an experiment using 0.5 µM of…

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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Drug D reversibly binds to enzyme E and inhibits its activity toward substrate S. D binds equally well whether or not S is bound. Sketch a graph of the expected 1/v vs. 1/[S] relationship for: A) The enzyme reacting with S in the absence of drug D, B) The enzyme reacting with S in the presence of a small amount of drug D, and C) The enzyme reacting with S in the presence of a large amount of drug D.
The Michaelis-Menten equation is often used to describe the kinetic characteristics of an enzyme-catalyzed reaction. Vmax [S] Km + [S] where v is the velocity, or rate, Vmax is the maximum velocity. K is the Michaelis-Menten constant, and [S] is the substrate concentration. A graph of the Michaelis-Menten equation is a plot of a reaction's initial velocity (ro) at different substrate concentrations ([S]). First, move the line labeled Vmax to a position that represents the maximum velocity of the enzyme. Next, move the line labeled 1/2 Vmax to its correct position. Then, move the line labeled Km to its correct position. Estimate the values for Vmax and Km- Vmax= µM/min v (µM/min) 300 275 250 225 200 175 150 125 100 75 50 Km = 25 K 0 10 20 30 V max 40 50 [S] (M) 1/2 V max Michaelis-Menten curve 60 70 80 90 100 HM
Find kcat for a reaction in which Vmax is 4 × 10-4 mol-min-1 and the reaction mixture contains one nanogram of enzyme. The molecular weight of the enzyme is 200,000 Da (1 Da = 1 g/mol). 2 x 10-13 min-1 2 x 10-11 min-¹ 80 min-¹ 8 x 107 min-¹ 8 x 10¹0 min-¹
For an enzyme kinetics experiment, a student prepared a reaction mixture by mixing 450 microliters of 0.75mM PNPP with 4.25ml of 0.2M Tris-HCl buffer. When he is ready to measure the absorbance, he added 0.3ml of Alkaline Phosphatase to the mixture and mixed thoroughly. What is the substrate concentration at the beginning of the reaction in mM ?
You obtain a calculated Vmax of 4.26uM/s and a Km of 122.5uM from a kinetics experiment performed using 0.5uM enzyme. What is the catalytic efficiency of this enzyme?
A research group discovers a new version of happyase, which they call happyase*, that catalyzes the chemical reaction: HAPPY-SAD The researchers begin to characterize the enzyme. The researchers determined the kcat of the enzyme to be 452 s-1. In a separate experiment with [E;) at 1.5 nM and [HAPPY) at 38 µM, the researchers find that Vo is equal to 320 nM s-1. What is the measured Km of happyase* for its substrate HAPPY? Make sure to include units in the answer.
During a test of kinetics of an enzyme-catalyzed reaction, the following data were recorded: a. Determine the Michaelis-Menten constant for the reaction with no inhibitor present at 30 °C and at 49.6 °C. b. Determine the maximum velocity of the uninhibited reaction at 30 °C and an enzyme concentration of 1.6 g/L. c. Determine the Ki for the inhibitor at 30 °C and decide what type of inhibitor is being used.
You are working at a major pharmaceutical company, and you have purified an engineered enzyme, and you need to determine the protein stability (kJ/mol). Accordingly, you have collected equilibrium unfolding data using the chemical denaturant urea at 20°C, pH 7.5 and I atmosphere using fluorescence spectroscopy. a) Determine the protein stability (AG [kJ/mol]) via nonlinear least squares (using the available data). b) Write the partial differential equation (i.e., general functional form, variable, constants). c) Describe what would happen to the isotherm if the temperature was increased to 25 °C. Urea [M] 0 0.25 0.5 0.75 1 1.25 1.5 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5 FL 340nm 316 315.5 315 314.5 314 315 300 275 225 125 75 60 55 54 53 52.5 52.25 52 51.75 51.5 dG = Vdp-SdT+μA dnд + μB dng dGp = μA dnA+ μg dng A = Folded State B = Unfolded State
Explain how the observation that reaction (B) runs faster than reaction (A) is related to the enzyme catalysis.
Please use the graph below to explain the differences between the 2 enzymes whose activities are plotted (enzyme 1-blue and enzyme 2-red). Using appropriate biochemical terminology, how do these differences affect the activity and function of Enzyme 1 versus Enzyme 2? Reaction velocity (vo) Vmax Vmax 2 0 0 Enzyme 1 Enzyme 2 [Substrate]
A purified protein fraction has a total sample volume of 360 µL. The sample has a corrected A280 of 0.484, and the blank corrected A280 was 0.052. (Both values were measured with a path length of 1.00 cm.) If 5.00 µL of the sample was used in a reaction, calculate the mass of protein in the reaction (in µg).
The following data have been obtained for two different initial enzyme concentrations for an enzyme-catalyzed reaction. [E]=0.015 g/l) (g/l-min) [S] (g/l) v([E]=0.00875 g/l) (g/l-min) 1.14 20.0 0.67 0.87 10.0 0.51 0.70 6.7 0.41 0.59 5.0 0.34 0.50 4.0 0.29 0.44 3.3 0.39 2.9 0.35 2.5 a. Find K b. Find V for [E]=0.015 g/l. c. Find V for [E]=0.00875 g/l. d. Find k2. Use Eddie-Hostee plot to find your answer. Compare your result using Hanes- Wolf plot.

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