The hydrolysis of pyrophosphate to orthophosphate drives biosynthetic reactions such as DNA synthesis. In Escherichia coli, a pyrophosphatase catalyzes this hydrolytic reaction. The pyrophosphatase has a mass of 120 kDa and consists of six identical subunits. A unit of activity for this enzyme, U, is the amount of enzyme that hydrolyzes 10 µmol of pyrophosphate in 15 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]T 1.12 ×10¹1 If each enzyme subunit has one active site, how many micromoles of active sites, or [E]T, are there in 1 mg of enzyme? Keat Incorrect || 8.33 x10³ What is the turnover number, or keat, of the enzyme? Incorrect μmol. sl. mg-1 1.34 X107 μmol-mg-1
The hydrolysis of pyrophosphate to orthophosphate drives biosynthetic reactions such as DNA synthesis. In Escherichia coli, a pyrophosphatase catalyzes this hydrolytic reaction. The pyrophosphatase has a mass of 120 kDa and consists of six identical subunits. A unit of activity for this enzyme, U, is the amount of enzyme that hydrolyzes 10 µmol of pyrophosphate in 15 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]T 1.12 ×10¹1 If each enzyme subunit has one active site, how many micromoles of active sites, or [E]T, are there in 1 mg of enzyme? Keat Incorrect || 8.33 x10³ What is the turnover number, or keat, of the enzyme? Incorrect μmol. sl. mg-1 1.34 X107 μmol-mg-1
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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![## Enzyme Kinetics: Pyrophosphatase in E. coli
**Overview:**
The hydrolysis of pyrophosphate to orthophosphate is crucial for biosynthetic reactions such as DNA synthesis. In *Escherichia coli*, this reaction is catalyzed by pyrophosphatase. Understanding the kinetics of this enzyme involves calculating several parameters including V_max, [E]_T, and k_cat.
1. **V_max Calculation:**
- **Question:** When [S] >> K_M, how many micromoles of substrate can 1 mg of enzyme hydrolyze per second?
- **User Input:** 1.12 × 10^11 μmol · s^-1 · mg^-1
- **Status:** Incorrect
2. **[E]_T Calculation:**
- **Question:** If each enzyme subunit has one active site, how many micromoles of active sites, or [E]_T, are there in 1 mg of enzyme?
- **User Input:** 8.33 × 10^3 μmol · mg^-1
- **Status:** Incorrect
3. **k_cat Calculation:**
- **Question:** What is the turnover number, or k_cat, of the enzyme?
- **User Input:** 1.34 × 10^7 s^-1
- **Status:** Incorrect
**Diagram Explanation:**
The image provides text input boxes for each of the calculations. The user entered values are highlighted in light gray with a red border indicating incorrect answers.
### Important Notes:
- V_max represents the maximum rate of reaction when the enzyme is saturated with substrate.
- [E]_T defines the total enzyme concentration.
- k_cat, the turnover number, indicates the number of substrate molecules converted per enzyme molecule per second.
Understanding these parameters helps elucidate the enzyme's efficiency and catalytic capacity in cellular processes.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fc94cb5d1-997a-49d0-b0ef-9ec02bf0a187%2F12176158-771c-47eb-afc6-4529e2c8a83b%2Fozqrpv4_processed.png&w=3840&q=75)
Transcribed Image Text:## Enzyme Kinetics: Pyrophosphatase in E. coli
**Overview:**
The hydrolysis of pyrophosphate to orthophosphate is crucial for biosynthetic reactions such as DNA synthesis. In *Escherichia coli*, this reaction is catalyzed by pyrophosphatase. Understanding the kinetics of this enzyme involves calculating several parameters including V_max, [E]_T, and k_cat.
1. **V_max Calculation:**
- **Question:** When [S] >> K_M, how many micromoles of substrate can 1 mg of enzyme hydrolyze per second?
- **User Input:** 1.12 × 10^11 μmol · s^-1 · mg^-1
- **Status:** Incorrect
2. **[E]_T Calculation:**
- **Question:** If each enzyme subunit has one active site, how many micromoles of active sites, or [E]_T, are there in 1 mg of enzyme?
- **User Input:** 8.33 × 10^3 μmol · mg^-1
- **Status:** Incorrect
3. **k_cat Calculation:**
- **Question:** What is the turnover number, or k_cat, of the enzyme?
- **User Input:** 1.34 × 10^7 s^-1
- **Status:** Incorrect
**Diagram Explanation:**
The image provides text input boxes for each of the calculations. The user entered values are highlighted in light gray with a red border indicating incorrect answers.
### Important Notes:
- V_max represents the maximum rate of reaction when the enzyme is saturated with substrate.
- [E]_T defines the total enzyme concentration.
- k_cat, the turnover number, indicates the number of substrate molecules converted per enzyme molecule per second.
Understanding these parameters helps elucidate the enzyme's efficiency and catalytic capacity in cellular processes.
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