The muscle isozyme of lactate dehydrogenase is inhibited by lactate.Steady state kinetic analysis yielded the following data, with lactateeither absent or present at a fixed concentration. (a) Pyruvate is the substrate whose concentration is varied in oneplot, NADH in the other. Identify each. Use an arrow and the appro-priate letter (b, c, d, or e) to identify each of the following.(b) Reciprocal of Vmax for the uninhibited enzyme.(c) The line representing data obtained in the presence of lactateacting as a competitive inhibitor with respect to the variablesubstrate.(d) The line representing data obtained in the presence of lactateacting as a mixed inhibitor with respect to the variable substrate.

Enzymes are proteinaceous substances that are capable of catalyzing chemical reactions of biological…

Answered: The muscle isozyme of lactate…

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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From the following data of an enzymatic reaction, determine the type of inhibition, the KM for the substrate and Ki for the enzyme-inhibitor complex. [S] mM 2.0 3.0 4.0 10.0 15.0 [P] mM/h (without inhibitor) 139 179 213 313 370 [P] mM/h ([I]=6mM) 88 121 149 257 313
Tube 1 contains water, pyrocatechol, potato enzyme extract; Tube 2 contains water, pyrocatechol, potato enzyme extract, and phenylthiourea. What do these results show about the effect of phenylthiourea on the reaction with tyrosinase, and what role does phenylthiourea play in this reaction? Tube 1 Tube 2 MacBook Air ) F12 4) FI1 II ER >> 000 吕0 F3 F4
The brown discoloration of apples and potatoes is due to an enzyme catalyzed chemical reaction. What is the enzyme that catalyzes this reaction? What is the substrate(s) of this reaction? What is the product(s) of this reaction? Does this reaction require a cofactor, if so which one?
The accompanying figure shows three Lineweaver–Burk plots for enzymereactions that have been carried out in the presence, or absence, of aninhibitor. Indicate what type of inhibition is predicted based on eachLineweaver–Burk plot. For each plot indicate which line corresponds to thereaction without inhibitor and which line corresponds to the reaction withinhibitor present.
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
The enzyme pyruvate carboxylase is discovered in a bacterium that was thought not to contain it; in this case study, you’ll see how researchers study and characterize the enzyme, and, ultimately, show how it fits into a metabolic pathway. Following purification of the PYC enzyme by avidin-Sepharose affinity chromatography, the investigators carried out several experiments to characterize the enzyme. First, they ran samples of the enzyme on denaturing and non-denaturing gels; the results are shown in the figure to the right. In addition, they ran the protein through a calibrated gel filtration column, the results of which indicated that the PYC enzyme had a molecular weight of 540 kiloDaltons. In the figure, the rightmost column are where molecular weight standards of various sizes would occur if they’d been on the gels. The catalytic properties of the PYC enzyme were assessed following purification. The activity of the enzyme was assayed in the presence of ATP, pyruvate, bicarbonate…
In bacteria, isocitrate dehydrogenase is regulated by phosphorylation of a specific Ser residue in the enzyme active site. X-ray structures of the phosphorylated and the nonphosphorylated enzyme show no significant conformational differences. How does phosphorylation regulate isocitrate dehydrogenase activity? O The phosphoryl group sterically hinders the substrate. O The phosphorylation bears a negative charge, which repels the substrate. O The phosphoryl group attracts positively charged Ca2* cations, which block the active site on the enzyme. None of the above.
If a slight deficiency in the Vitamin B1 derivative Thiamine Pyrophosphate (TPP) leads to an accumulation of substrates for reactions utilizing this cofactor, A) what substrates would ‘accumulate’ in a human after eating a an enormous amount of sugar-laden Halloween candy, AND what would be the regulatory consequences on carbohydrate metabolism? B) What substrates would accumulate in yeast cells cultured under anaerobic (no oxygen) conditions AND what would be the regulatory consequences on carbohydrate metabolism? C) What substrates would accumulate in plant cells incorporating carbon and generating energy solely using photosynthesis?
If a slight deficiency in the Vitamin B1 derivative Thiamine Pyrophosphate (TPP) leads to an accumulation of substrates for reactions utilizing this cofactor, A) what substrates would ‘accumulate’ in a human after eating a an enormous amount of sugar-laden Halloween candy, AND what would be the regulatory consequences on carbohydrate metabolism? B) what substrates would accumulate in yeast cells cultured under anaerobic (no oxygen) conditions AND what would be the regulatory consequences on carbohydrate metabolism? C) and lastly, what substrates would accumulate in plant cells incorporating carbon and generating energy solely using photosynthesis?
The protein catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide:2 H2O2 (aq) → 2 H2O (l) + O2 (g)and has a Michaelis-Menten constant of 25 × 10-3 mol·dm-3 and a turnover number of 4.0×107s-1.The total enzyme concentration is 0.016×10-6 mol·dm-3 and the initial substrate concentration is4.32×10-6 mol·dm-3 Calculate the maximum reaction rate (????) for this enzyme, and the initial rateof this reaction. Note that catalase has a single active site.
The lipase substrate emulsion contains 0.500 mg of olive oil per 3 mL Also, the molar mass of the olive oil is 885 g/mol. If all of the olive oil in a 3 mL reaction is "digested" by pancreatic lipase in a reaction, how many molecules of olive oil have been degraded?
From a series of flasks with a constant concentration of enzyme the following initial velocities weretaken, they were obtained as a function of the concentration of the substrate.a) Calculate the KM and Vmax kinetic parameters of the three forms (Lineweaver-Burk, Eadie-Hofstee, Dixon).b) Analyze which are the atypical data that cause a low correlation, which can be eliminated and explain youranswer.

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