Q11: The hydrolysis of pyrophosphate to orthophosphate drives biosynthetic reactions such as DNA synthesis. In Escherichia coli, apyrophosphatase catalyzes this hydrolytic reaction. The pyrophosphatase has a mass of 120 kDa and consists of six identicalsubunits. A unit of activity for this enzyme, U, is the amount of enzyme that hydrolyzes 10 μmol of pyrophosphate in15 minutes. The purified enzyme has a Vmax of 2800 U per milligram of enzyme.When [S] >> KM, how many micromoles of substrate can 1 mg of enzyme hydrolyze per second?Vmax[E]T1.12 x10¹1IncorrectIf each enzyme subunit has one active site, how many micromoles of active sites, or [E]T, are there in 1 mg of enzyme?Keat =8.33 x10³IncorrectWhat is the turnover number, or keat, of the enzyme?1.34 X107μmol. s-¹.mg-¹Incorrectμmol-mg-18-1

Enzymes are proteinaceous entities involved in chemical reactions contributing to the precedence of…

Answered: The hydrolysis of pyrophosphate to…

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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Human blood serum contains a class of enzymes known as acid phosphatases, which hydrolyze biological phosphate esters under slightly acidic conditions (pH 5.0): R-O-P-O3-2 + H2O --> R-OH + HO-P-O3-2. Acid phosphatases are produced by erythrocytes, the liver, kidney, spleen, and prostate gland. The enzyme from the prostate gland is clinically important because an increased activity in the blood is frequently an indication of cancer of the prostate gland. The phosphatase from the prostate gland is strongly inhibited by tartrate ion, but acid phosphatases from other tissues are not. How can this information be used to develop a commercial specific procedure for measuring the activity of the acid phosphatase of the prostate gland in human blood serum? * 1. Prostate cancer cannot be diagnosed biochemically. 2. Use tartrate to inhibit phosphatase from prostate gland and then subtract the results from the total serum enzyme activities to get an…
A glycolytic intermediate may be used to make the glycerol 3-phosphate necessary for the production of glycerophospholipids. For this conversion, provide a reaction sequence.
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.
Intramitochondrial ATP concentrations are about 5 mM, and phos- phate concentration 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 concentra- tion of ATP plus half the concentration of ADP divided by the total adenine nucleotide concentration: [ATP] + 1/2[ADP] [ATP] + [ADP] + [AMP]
Human blood serum contains a class of enzymes known as acid phosphatases, which hydrolyze biological phosphate esters under slightly acidic conditions (pH 5.0): Acid phosphatases are produced by erythrocytes and by the liver, kidney, spleen, and prostate gland. The enzyme of the prostate gland is clinically important, because itsincreased activity in the blood can be an indication of prostate cancer. The phosphatase from the prostate gland is strongly inhibited by tartrate ion, but acid phosphatases from other tissues are not. How can this information be used to develop a specific procedure for measuring the activity of the acid phosphatase of the prostate gland in human blood serum?
Intramitochondrial ATP concentrations are about 5 mM, and phosphate concentration 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 condi- tions. The energy charge is the concentration of ATP plus half the concen- tration of ADP divided by the total adenine nucleotide concentration: [ATP] + 1/2[ADP] [ATP] + [ADP] + [AMP]
The pKa for histidine is pKa = 6.1 while that for cysteine is pKa = 8.0 2. Assume that both histidine and cysteine are catalytic groups for a particular enzyme. Assume also that the side chain of cysteine must be in the deprotonated form. Estimate the pH at which the catalytic activity of this enzyme is the maximum and sketch a pH-activity graph.
Hexokinase is an important enzyme in the metabolism of glucose. If theconcentration of hexokinase in our eukaryotic cell is 20 μM, how many glucose molecules are present per hexokinase molecule?
The active site of an enzyme that uses a general acid-base catalytic mechanism contains a Glu and an Asp residue (both of which are essential for catalysis) with pKa values of 5.9 and 4.5, respectively. If the enzyme is found in the lysosome (pH = 5.2), which residue will act as the general acid and which will act as the general base during the initial steps of the reaction?
Carbonyl cyanide 4- ( trifluoromethoxy ) phenylhydrazone (FCCP) is a proton ionophore : it enables protons to pass freely through membranes. Treatment of E. coli with FCCP prevents the accumulation of lactose in these cells. Explain.
The “keto diet” is a dietary regimen in which carbohydrates are severely restricted, protein intake is low, and fat comprises 70–90% of daily calories. The diet causes “nutritional ketosis,” which is a different metabolic state than the ketosis that occurs in an untreated diabetic. The normal ketone body concentration is less than 0.6 mM. Explain why an individual on the keto diet may have a blood ketone body concentration of up to 3 mM. What biochemical pathways are active in an individual adhering to the keto diet? What pathways are largely inactive? Protein intake is kept low because a high-protein diet would inhibit ketosis. Explain why. Why might the keto diet lead to weight loss?
The venom of the Eastern diamondback rattler and the Indian cobra contains phospholipase A2, which catalyzes the hydrolysis of fatty acids at the C-2 position of glycerophospholipids. The phospholipid breakdownproduct of this reaction is lysolecithin (lecithin is phosphatidylcholine). At high concentrations, this and other lysophospholipids act as detergents, dissolving the membranes of erythrocytes and lysing the cells. Extensive hemolysis may be lifethreatening.(a) All detergents are amphipathic. What are the hydrophilic and hydrophobic portions of lysolecithin?(b) The pain and inflammation caused by a snake bite can be treated with certain steroids. What is the basis of this treatment?(c) Though the high levels of phospholipase A2 in venom can be deadly, this enzyme is necessary for a variety of normal metabolic processes. What are these processes?

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